what is after the mean in math code example

Example 1: mean

#the plan is to have a boring mean
def mean(arr): # mean
  return sum(arr)/len(arr)

Example 2: mean

#the plan is to remove all values that are zero

def mean(arr): # mod_mean
  arr = list(filter(lambda n:n!=0,arr))
  return sum(arr)/len(arr)