Answer:
def mins_by_phone(phone):
if phone in self.phones:
min_sum = 0
for call in calls:
min_sum += call
return min_sum
else:
return 0
Explanation:
The mins_by_phone function above is the Phone class method. It checks for the presence of the argument value in the self.phones instance variable, which is a list and sums up and returns the call minutes in the call list.
