input: 
  def most_common(nums):
      """Return the most common elements in an array of integers.
      >>> most_common([3, 4, 1, 2, 5, 3, 3])
      [3]
      >>> most_common([1, 2, 3, 2, 1, 3, 4, 4, 5, 4])
      [4]
      """
      counts = {}
      for num in nums:
          if num not in counts:
              counts[num] = 0
          counts[num] += 1
      max_count = max(counts.values())
      return [num for num, count in counts.items() if count == max_count]
  
output:     counts = {}
      for num in nums:
          if num not in counts:
              counts[num] = 0
          counts[num] += 1
      max_count = max(counts.values())
      return [num for num, count in counts.items() if count == max_count]