input: 
  from typing import List, Optional
  
  
  def find_pair(lst: List[int], target: int) -> Optional[List[int]]:
      """ Given a list of numbers and a target number, find a pair of numbers from the given 
      list that add up to the given target.
      >>> find_pair([1, 2, 3, 4, 4, 5, 6], 8)
      [4, 4]
      >>> find_pair([1, 2, 3, 4, 4, 5, 6], 7)
      [1, 6]
      """
      for i in range(len(lst)):
          if (target - lst[i]) in lst[i+1:]:
              return [lst[i], target-lst[i]]
  
output:     return None