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(5, [1, 2, 3, 4])==False
  assert element_exists("a", [1, 2, 3, "a"])==True
  assert element_exists(7, [])==False
output: def element_exists(element, lst):
      return element in lst