fix: Correct reference to Sequence

Exercises/ex2_5.md

@@ -175,7 +175,7 @@ function.
 
 import collections
 ...
-class RideData(collections.Sequence):
+class RideData(collections.abc.Sequence):
     def __init__(self):
         self.routes = []      # Columns
         self.dates = []
@@ -204,7 +204,7 @@ into 4 separate `append()` operations.
 # readrides.py
 ...
 
-class RideData(collections.Sequence):
+class RideData(collections.abc.Sequence):
     def __init__(self):
         # Each value is a list with all of the values (a column)
         self.routes = []

Exercises/soln2_5.md

@@ -93,7 +93,7 @@ def read_rides_as_columns(filename):
 # The great "fake"
 
 import collections
-class RideData(collections.Sequence):
+class RideData(collections.abc.Sequence):
     def __init__(self):
         # Each value is a list with all of the values (a column)
         self.routes = []