input: Write a function to check if an element exists within a given list of integers. Return True if the element exists, otherwise return False.
  def element_exists(elem, list_int):
    return elem in list_int
  assert element_exists(5, [1, 2, 3, 4, 5])==True
  assert element_exists(10, [1, 2, 3, 4, 5])==False
  assert element_exists(0, [])==False
  assert element_exists(3, [1, 2, 3, 4, 5])==True
output: def element_exists(elem, list_int):
    return elem in list_int