# Count the number of occurences of an item in a list using a for loop
# Parameters:
#   data: The list containing the items to count
#   what: The item that we are looking for
# Returns: The number of times that what occurs in data
def count(data, what):
  total = 0
  for item in data:
    if item == what:
      total = total + 1
  return total

# Count the number of occurences of an item in a list using a while loop that
# modifies the list
# Parameters:
#   data: The list containing the items to count
#   what: The item that we are looking for
# Returns: The number of times that what occurs in data
def count2(data, what):
  total = 0
  while data != []:
    item = data.pop()
    if item == what:
      total = total + 1
  return total

print("Using the count function (for loop version):")
values = ["a", "b", "c", "a", "a", "b"]
print("  values is currently", values)
print("  How many times does a appear in values?", count(values, "a"))
print("  values is currently", values)
print("  How many times does b appear in values?", count(values, "b"))
print("  values is currently", values)
print("  How many times does c appear in values?", count(values, "c"))
print("  values is currently", values)
print()

print("Using the count2 function (while loop version):")
values = ["a", "b", "c", "a", "a", "b"]
print("  values is currently", values)
print("  How many times does a appear in values?", count2(values, "a"))
print("  values is currently", values)
print("  How many times does b appear in values?", count2(values, "b"))
print("  values is currently", values)
print("  How many times does c appear in values?", count2(values, "c"))
print("  values is currently", values)