input: Write a python function to calculate the mode of a sequence of numbers.
  assert calculate_mode([1, 2, 3, 3, 3, 4, 5, 1, 2, 2, 2])==2
  assert calculate_mode([7, 8, 9, 7, 7, 8, 8, 8, 9])==8
  assert calculate_mode([1, 1, 1, 2, 3, 4, 5, 5, 5, 5, 6])==5
output: def calculate_mode(numbers):
      from collections import Counter
      count = Counter(numbers)
      mode, max_count = count.most_common(1)[0]
      return mode