input: 
  def element_exists(elem, list_int):
      """Check if an element exists within a given list of integers.
      >>> element_exists(5, [1, 2, 3, 4, 5])
      True
      >>> element_exists(6, [1, 2, 3, 4, 5])
      False
      """
      return elem in list_int
  
output:     for item in list_int:
          if item == elem:
              return True
      return False