diff --git a/.gitignore b/.gitignore
index b6e47617d..badc4b460 100644
--- a/.gitignore
+++ b/.gitignore
@@ -127,3 +127,8 @@ dmypy.json
 
 # Pyre type checker
 .pyre/
+
+# generated files
+*stocklog.csv
+
+.DS_Store
diff --git a/Work/bounce.py b/Work/bounce.py
index 3660ddd82..60ff9a6dc 100644
--- a/Work/bounce.py
+++ b/Work/bounce.py
@@ -1,3 +1,13 @@
 # bounce.py
 #
 # Exercise 1.5
+
+def main():
+    cur_height = 100
+
+    for bounce in range(10):
+        cur_height *= 3/5
+        print(bounce+1, round(cur_height, 4))
+
+if __name__ == "__main__":
+    main()
diff --git a/Work/fileparse.py b/Work/fileparse.py
deleted file mode 100644
index 1d499e733..000000000
--- a/Work/fileparse.py
+++ /dev/null
@@ -1,3 +0,0 @@
-# fileparse.py
-#
-# Exercise 3.3
diff --git a/Work/mortgage.py b/Work/mortgage.py
index d527314e3..53b71d23b 100644
--- a/Work/mortgage.py
+++ b/Work/mortgage.py
@@ -1,3 +1,29 @@
 # mortgage.py
 #
 # Exercise 1.7
+
+def calc(start, end, extra_payment):
+    principal = 500000.0
+    rate = 0.05
+    payment = 2684.11
+    npayments = 0
+    total_paid = 0.0
+
+    while principal > 0:
+        npayments = npayments + 1
+        cur_payment = payment + extra_payment if start <= npayments <= end else payment
+        remaining = principal * (1+rate/12)
+        if cur_payment > remaining: # overpayment?
+            cur_payment = remaining
+        principal = remaining - cur_payment 
+        total_paid = total_paid + cur_payment
+        print(f'{npayments} {cur_payment:>8.2f} {total_paid:>10.2f} {principal:>10.2f}')
+
+    print(f'{34*"-"}\nTotal paid: {total_paid:0.2f} in {npayments} months')
+
+if __name__ == "__main__":
+    start = input('start month: ')
+    end = input('end month: ')
+    extra_payment = input('extra payment: ')
+    args = [int(s) for s in (start, end, extra_payment)]
+    calc(*args)
diff --git a/Work/pcost.py b/Work/pcost.py
deleted file mode 100644
index e68aa20b4..000000000
--- a/Work/pcost.py
+++ /dev/null
@@ -1,3 +0,0 @@
-# pcost.py
-#
-# Exercise 1.27
diff --git a/Work/porty-app/portfolio.csv b/Work/porty-app/portfolio.csv
new file mode 100644
index 000000000..6c16f65b5
--- /dev/null
+++ b/Work/porty-app/portfolio.csv
@@ -0,0 +1,8 @@
+name,shares,price
+"AA",100,32.20
+"IBM",50,91.10
+"CAT",150,83.44
+"MSFT",200,51.23
+"GE",95,40.37
+"MSFT",50,65.10
+"IBM",100,70.44
diff --git a/Work/porty-app/porty/fileparse.py b/Work/porty-app/porty/fileparse.py
new file mode 100644
index 000000000..eae23874c
--- /dev/null
+++ b/Work/porty-app/porty/fileparse.py
@@ -0,0 +1,63 @@
+# fileparse.py
+#
+# Exercise 3.3
+import csv
+import logging
+log = logging.getLogger(__name__)
+
+def parse_csv(data, 
+              select=None, 
+              types=None, 
+              has_headers=True, 
+              delimiter=',', 
+              silence_errors=False):
+    """Parse a CSV stream into a list of records
+       structured as dicts.
+
+    :data:          file-like object
+    :select:        selected columns
+    :types:         conversion functions
+    :has_headers
+    :delimiter
+    :silence_errors
+    :returns: list of records (dicts)
+
+    """
+    if select and not has_headers:
+        raise RuntimeError('select argument requires column headers')
+
+    if select and types and len(select) != len(types):
+        raise RuntimeError('select and types lists must have the same shape')
+
+    # type conversion helper
+    def convert(rows):
+        assert types
+        for i, row in enumerate(rows, 1):
+            try:
+                yield [t(val) for t, val in zip(types, row)] 
+            except ValueError as e:
+                if not silence_errors:
+                    log.warning("Row %d: Couldn't convert %s", i, row)
+                    log.debug("Row %d: Reason %s", i, e)
+
+    rows = csv.reader(data, delimiter=delimiter)
+    if has_headers:
+        headers = next(rows)
+
+    rows = (r for r in rows if r) # generate only non-empty rows
+
+    # filter columns
+    if select:
+        indices = [headers.index(c) for c in select]
+        headers = select
+        rows = ([row[i] for i in indices] for row in rows)
+
+    # convert to types
+    if types:
+        rows = convert(rows)
+
+    # package to records
+    if has_headers:
+        return [dict(zip(headers, row)) for row in rows] 
+    else:
+        return [tuple(r) for r in rows]
diff --git a/Work/porty-app/porty/follow.py b/Work/porty-app/porty/follow.py
new file mode 100644
index 000000000..91326af09
--- /dev/null
+++ b/Work/porty-app/porty/follow.py
@@ -0,0 +1,43 @@
+# follow.py
+import os, sys
+import time
+
+def follow(logfile):
+    with open(logfile) as f:
+        f.seek(0, os.SEEK_END) # move file pointer 0 bytes from EOF
+
+        while True:
+            line = f.readline()
+            if not line:
+                time.sleep(0.1) # sleep briefly & retry
+                continue
+            yield line
+
+def filematch(lines, substr):
+    for line in lines:
+        if substr in line:
+            yield line
+
+def convert(lines):
+    for line in lines:
+        fields = line.split(',')
+        name = fields[0].strip('"')
+        price = float(fields[1])
+        change = float(fields[4])
+        yield (name, price, change)
+
+def ticker(portfile, tickerfile):
+    import report
+    portfolio = report.read_portfolio(portfile)
+    for name, price, change in convert(follow(tickerfile)):
+        if name in portfolio:
+            print(f'{name:>10s} {price:>10.2f} {change:>10.2f}')
+
+def main(argv):
+    if len(argv) != 3:
+        raise SystemExit(f'usage: {argv[0]} portfile tickerfile')
+
+    ticker(argv[1], argv[2])
+
+if __name__ == "__main__":
+    main(sys.argv)
diff --git a/Work/porty-app/porty/pcost.py b/Work/porty-app/porty/pcost.py
new file mode 100755
index 000000000..cbe2d0600
--- /dev/null
+++ b/Work/porty-app/porty/pcost.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+
+# pcost.py
+#
+# Exercise 1.27
+
+import csv
+import sys
+from . import report
+
+def portfolio_cost(path):
+    portfolio = report.read_portfolio(path)
+    return portfolio.total_cost
+
+def main(argv):
+    if len(argv) != 2:
+        raise SystemExit(f'Usage: {argv[0]} portfile')
+    total = portfolio_cost(argv[1])
+    print(f'Total cost ${total}')
+
+if __name__ == "__main__":
+    import sys
+    main(sys.argv)
diff --git a/Work/porty-app/porty/portfolio.py b/Work/porty-app/porty/portfolio.py
new file mode 100644
index 000000000..73c08a4f4
--- /dev/null
+++ b/Work/porty-app/porty/portfolio.py
@@ -0,0 +1,48 @@
+# portfolio.py
+
+from . import fileparse
+from . import stock
+
+class Portfolio:
+    def __init__(self):
+        self._holdings = []
+
+    def append(self, holding):
+        if not isinstance(holding, stock.Stock):
+            raise TypeError('Expected a stock instance')
+        self._holdings.append(holding)
+
+    @classmethod
+    def from_csv(cls, lines, **opts):
+        self = cls()
+        portfolio_dicts = fileparse.parse_csv(lines, 
+                                              select=['name', 'shares', 'price'],
+                                              types=[str, int, float], 
+                                              **opts)
+        for d in portfolio_dicts:
+            self.append(stock.Stock(**d))
+        
+        return self
+
+    def __iter__(self):
+        return self._holdings.__iter__()
+
+    def __len__(self):
+        return len(self._holdings)
+
+    def __getitem__(self, index):
+        return self._holdings[index]
+
+    def __contains__(self, name):
+        return any(s.name==name for s in self._holdings)
+
+    @property
+    def total_cost(self):
+        return sum(s.cost for s in self._holdings)
+
+    def tabulate_shares(self):
+        from collections import Counter
+        total_shares = Counter()
+        for s in self._holdings:
+            total_shares[s.name] += s.shares
+        return total_shares
diff --git a/Work/porty-app/porty/report.py b/Work/porty-app/porty/report.py
new file mode 100755
index 000000000..4bc91b8fe
--- /dev/null
+++ b/Work/porty-app/porty/report.py
@@ -0,0 +1,64 @@
+#!/usr/bin/env python
+# report.py
+#
+# Exercise 2.4
+
+import csv
+from . import fileparse
+from . import tableformat
+from .stock import Stock
+from .portfolio import Portfolio
+import logging
+logging.basicConfig(
+        # filename = 'app.log',
+        # filemode = 'w',
+        level = logging.WARNING,
+        )
+
+def read_portfolio(path, **opts):
+    """
+    Read a stock portfolio file into a list of dictionaries with keys
+    name, shares, and price.
+    """
+    with open(path, 'rt') as file:
+        portfolio = Portfolio.from_csv(file)
+    return portfolio
+
+def read_prices(path):
+    """
+    Parses price data file into stock price dictionary
+    """
+    with open(path, 'rt') as file:
+        prices = fileparse.parse_csv(file, types=[str, float], has_headers=False)
+    return {n:p for n, p in prices}
+
+def make_report(portfolio, prices):
+    return [(s.name, s.shares, prices[s.name], prices[s.name] - s.price) 
+            for s in portfolio]
+
+def print_report(report, formatter):
+    formatter.headings(['Name', 'Shares', 'Price', 'Change'])
+    for name, shares, price, change in report:
+        formatter.row((name, shares, f'${price:0.2f}', f'{change:0.2f}'))
+
+def portfolio_report(path_portfolio, path_prices, fmt='txt'):
+    # collect report data
+    portfolio = read_portfolio(path_portfolio)
+    prices = read_prices(path_prices)
+    report = make_report(portfolio, prices)
+
+    # print it!
+    formatter = tableformat.create_formatter(fmt)
+    print_report(report, formatter)
+
+def main(argv):
+    if len(argv) < 3:
+        raise SystemExit(f'Usage: {argv[0]} portfile pricefile [format(txt|csv|html)]')
+    elif len(argv) == 3:
+        portfolio_report(argv[1], argv[2])
+    else: # optional format arg?
+        portfolio_report(argv[1], argv[2], fmt=argv[3])
+
+if __name__ == "__main__":
+    import sys
+    main(sys.argv)
diff --git a/Work/porty-app/porty/stock.py b/Work/porty-app/porty/stock.py
new file mode 100644
index 000000000..a9cb08441
--- /dev/null
+++ b/Work/porty-app/porty/stock.py
@@ -0,0 +1,32 @@
+from .typedproperty import String, Integer, Float
+
+class Stock(object):
+    """Represents stock holding."""
+    __slots__ = ('_name', '_shares', '_price')
+    name = String('name')
+    shares = Integer('shares')
+    price = Float('price')
+
+
+    def __init__(self, name, shares, price):
+        self.name = name
+        self.shares = shares
+        self.price = price
+
+    def __repr__(self):
+        return f"Stock('{self.name}', {self.shares}, {self.price})"
+    
+    def __str__(self):
+        return repr(self)
+    
+    def __unicode__(self):
+        return str(self)
+
+    @property
+    def cost(self):
+        return self.shares * self.price
+
+    def sell(self, n):
+        assert n <= self.shares
+        self.shares -= n
+        return self
diff --git a/Work/porty-app/porty/tableformat.py b/Work/porty-app/porty/tableformat.py
new file mode 100644
index 000000000..b420f20db
--- /dev/null
+++ b/Work/porty-app/porty/tableformat.py
@@ -0,0 +1,73 @@
+# tableformat.py
+
+def create_formatter(fmt):
+    formatters = {
+            'txt': TextTableFormatter,
+            'csv': CSVTableFormatter,
+            'html': HTMLTableFormatter,
+            }
+
+    if fmt not in formatters.keys():
+        raise FormatError(f'Unknown table format {fmt}')
+
+    return formatters[fmt]()
+
+def print_table(portfolio, columns, formatter):
+    formatter.headings(columns)
+    for s in portfolio:
+        data = [str(getattr(s, a)) for a in columns]
+        formatter.row(data)
+
+def stringify(row):
+    return (str(val) for val in row)
+    
+class TableFormatter:
+    """
+    Formatter ABC
+    """
+    def headings(self, headers):
+        """
+        Emit the table headings.
+        """
+        raise NotImplementedError()
+
+    def row(self, data):
+        """
+        Emit a single row of table data.
+        """
+        raise NotImplementedError()
+
+class TextTableFormatter(TableFormatter):
+    def headings(self, headers):
+        for h in headers:
+            print(f'{h:>10s}', end=' ')
+        print()
+        print(('-'*10 + ' ')*len(headers))
+
+    def row(self, data):
+        for d in stringify(data):
+            print(f'{d:>10s}', end=' ')
+        print()
+
+class CSVTableFormatter(TableFormatter):
+    def headings(self, headers):
+        print(','.join(headers))
+
+    def row(self, data):
+        print(','.join(stringify(data)))
+
+class HTMLTableFormatter(TableFormatter):
+    def headings(self, headers):
+        print('<tr>', end='')
+        for h in headers:
+            print(f'<th>{h}</th>', end='')
+        print('</tr>')
+
+    def row(self, data):
+        print('<tr>', end='')
+        for d in stringify(data):
+            print(f'<td>{d}</td>', end='')
+        print('</tr>')
+
+class FormatError(Exception):
+    pass
diff --git a/Work/porty-app/porty/test_pcost.py b/Work/porty-app/porty/test_pcost.py
new file mode 100644
index 000000000..1e4cd5475
--- /dev/null
+++ b/Work/porty-app/porty/test_pcost.py
@@ -0,0 +1,13 @@
+import unittest
+import pcost as pc
+
+class KnownOutput(unittest.TestCase):
+
+    def test_portfolio_cost(self):
+        self.assertEqual(pc.portfolio_cost('./Data/portfolio.csv'), 44671.15)
+
+    def test_missing_fields(self):
+        self.assertEqual(pc.portfolio_cost('Data/missing.csv'), 27381.15)
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Work/porty-app/porty/test_report.py b/Work/porty-app/porty/test_report.py
new file mode 100644
index 000000000..9f96fcdcc
--- /dev/null
+++ b/Work/porty-app/porty/test_report.py
@@ -0,0 +1,20 @@
+import unittest
+import report as rep
+from portfolio import Portfolio
+
+class KnownOutput(unittest.TestCase):
+
+    def test_read_portfolio(self):
+        self.assertEqual(len(rep.read_portfolio('./Data/portfolio.csv')), 7)
+
+    def test_missing_fields(self):
+        self.assertEqual(len(rep.read_portfolio('./Data/missing.csv')), 5)
+
+class PortfolioTests(unittest.TestCase):
+
+    def test_total_cost(self):
+        port = Portfolio(rep.read_portfolio('Data/portfolio.csv'))
+        self.assertEqual(port.total_cost, 44671.15)
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Work/porty-app/porty/test_stock.py b/Work/porty-app/porty/test_stock.py
new file mode 100644
index 000000000..93fb54b7f
--- /dev/null
+++ b/Work/porty-app/porty/test_stock.py
@@ -0,0 +1,39 @@
+# test_stock.py
+
+import unittest
+import stock
+
+class TestStock(unittest.TestCase):
+
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    def test_create(self):
+        s = stock.Stock('GOOG', 100, 490.1)
+        self.assertEqual(s.name, 'GOOG')
+        self.assertEqual(s.shares, 100)
+        self.assertEqual(s.price, 490.1)
+
+    def test_cost(self):
+        s = stock.Stock('GOOG', 100, 490.1)
+        self.assertEqual(s.cost, 49010.0)
+        
+    def test_sell(self):
+        s = stock.Stock('GOOG', 100, 490.1)
+        self.assertEqual(90, s.sell(10).shares)
+
+    def test_sell_too_much(self):
+        s = stock.Stock('GOOG', 100, 490.1)
+        with self.assertRaises(AssertionError):
+            s.sell(200)
+
+    def test_bad_shares(self):
+        s = stock.Stock('GOOG', 100, 490.1)
+        with self.assertRaises(TypeError):
+            s.shares = '200'
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Work/porty-app/porty/ticker.py b/Work/porty-app/porty/ticker.py
new file mode 100644
index 000000000..0110a4d81
--- /dev/null
+++ b/Work/porty-app/porty/ticker.py
@@ -0,0 +1,41 @@
+# ticker.py
+
+from .follow import follow
+import csv
+
+def stock_pipeline(stream, portfolio):
+    rows = csv.reader(stream)
+    # select columns
+    rows = ([r[i] for i in [0, 1, 4]] for r in rows)
+    # convert types
+    rows = ([func(val) for func, val in zip((str,float,float), r)] for r in rows)
+    # transform to dicts
+    rows = (dict(zip(('name', 'price', 'change'), r)) for r in rows)
+    # filter portfolio stocks
+    rows = (r for r in rows if r['name'] in portfolio)
+    return rows
+
+def ticker(portfile, logfile, fmt='txt'):
+    import report, tableformat
+
+    rows = stock_pipeline(follow(logfile), report.read_portfolio(portfile))
+
+    # print it!
+    formatter = tableformat.create_formatter(fmt)
+    formatter.headings(['Name', 'Price', 'Change'])
+    for r in rows:
+        formatter.row((r['name'], f"${r['price']}", r['change']))
+
+
+def main(args):
+    if len(args) < 3:
+        raise SystemExit('usage: ticker portfile logfile [fmt(txt|csv|html)]')
+
+    if len(args) == 3:
+        ticker(args[1], args[2])
+    else:
+        ticker(args[1], args[2], fmt=args[3])
+
+if __name__ == "__main__":
+    import sys
+    main(sys.argv)
diff --git a/Work/porty-app/porty/typedproperty.py b/Work/porty-app/porty/typedproperty.py
new file mode 100644
index 000000000..6a4bdffe0
--- /dev/null
+++ b/Work/porty-app/porty/typedproperty.py
@@ -0,0 +1,19 @@
+# typedproperty.py
+
+def typedproperty(name, expected_type):
+    private_name = '_' + name
+    @property
+    def prop(self):
+        return getattr(self, private_name)
+
+    @prop.setter
+    def prop(self, value):
+        if not isinstance(value, expected_type):
+            raise TypeError(f'Expected {expected_type}')
+        setattr(self, private_name, value)
+
+    return prop
+
+String  = lambda name: typedproperty(name, str)
+Integer = lambda name: typedproperty(name, int)
+Float   = lambda name: typedproperty(name, float)
diff --git a/Work/porty-app/prices.csv b/Work/porty-app/prices.csv
new file mode 100644
index 000000000..6bbcb2099
--- /dev/null
+++ b/Work/porty-app/prices.csv
@@ -0,0 +1,31 @@
+"AA",9.22
+"AXP",24.85
+"BA",44.85
+"BAC",11.27
+"C",3.72
+"CAT",35.46
+"CVX",66.67
+"DD",28.47
+"DIS",24.22
+"GE",13.48
+"GM",0.75
+"HD",23.16
+"HPQ",34.35
+"IBM",106.28
+"INTC",15.72
+"JNJ",55.16
+"JPM",36.90
+"KFT",26.11
+"KO",49.16
+"MCD",58.99
+"MMM",57.10
+"MRK",27.58
+"MSFT",20.89
+"PFE",15.19
+"PG",51.94
+"T",24.79
+"UTX",52.61
+"VZ",29.26
+"WMT",49.74
+"XOM",69.35
+
diff --git a/Work/porty-app/print-report.py b/Work/porty-app/print-report.py
new file mode 100644
index 000000000..89781bc2d
--- /dev/null
+++ b/Work/porty-app/print-report.py
@@ -0,0 +1,3 @@
+import sys
+from porty.report import main
+main(sys.argv)
diff --git a/Work/report.py b/Work/report.py
deleted file mode 100644
index 47d5da7b1..000000000
--- a/Work/report.py
+++ /dev/null
@@ -1,3 +0,0 @@
-# report.py
-#
-# Exercise 2.4
diff --git a/Work/sears.py b/Work/sears.py
new file mode 100644
index 000000000..df968fff7
--- /dev/null
+++ b/Work/sears.py
@@ -0,0 +1,15 @@
+# sears.py
+
+bill_thickness = 0.11 * 0.001    # Meters (0.11 mm)
+sears_height   = 442             # Height (meters)
+num_bills      = 1
+day            = 1
+
+while num_bills * bill_thickness < sears_height:
+    print(day, num_bills, num_bills * bill_thickness)
+    day = day + 1
+    num_bills = num_bills * 2
+
+print('Number of days', day)
+print('Number of bills', num_bills)
+print('Final height', num_bills * bill_thickness)