input: Write a function to check if an element exists within a given list of integers. If the element exists in the list return True, else return False.
  assert element_exists(5, [1, 2, 3, 4, 5])==True
  assert element_exists(6, [1, 2, 3, 4, 5])==False
  assert element_exists(0, [])==False
  assert element_exists("a", [1, 2, 3, "a", 5])==True
  assert element_exists([1, 2], [1, 2, 3, [1, 2], 5])==True
output: def element_exists(element, lst):
      return element in lst