Added solution code

Solutions/2_16/pcost.py

@@ -0,0 +1,32 @@
+# pcost.py
+
+import csv
+def portfolio_cost(filename):
+    '''
+    Computes the total cost (shares*price) of a portfolio file
+    '''
+    total_cost = 0.0
+
+    with open(filename) as f:
+        rows = csv.reader(f)
+        headers = next(rows)
+        for rowno, row in enumerate(rows, start=1):
+            record = dict(zip(headers, row))
+            try:
+                nshares = int(record['shares'])
+                price = float(record['price'])
+                total_cost += nshares * price
+            # This catches errors in int() and float() conversions above
+            except ValueError:
+                print(f'Row {rowno}: Bad row: {row}')
+
+    return total_cost
+
+import sys
+if len(sys.argv) == 2:
+    filename = sys.argv[1]
+else:
+    filename = input('Enter a filename:')
+
+cost = portfolio_cost(filename)
+print('Total cost:', cost)