input: Write a function to find the mode of a list of numbers.
  assert find_mode([1, 2, 3, 3, 4, 4, 4, 5]) == [4]
  assert find_mode([1, 1, 2, 2, 3, 3, 4]) == [1, 2, 3]
  assert find_mode([10, 10, 10, 5, 5, 5, 3]) == [10, 5]
output: def find_mode(numbers):
      from collections import Counter
      count = Counter(numbers)
      max_freq = max(count.values())
      return [num for num, freq in count.items() if freq == max_freq]