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; otherwise, return False.
  
  assert element_exists(5, [1, 3, 5, 7])==True
  assert element_exists(10, [2, 4, 6, 8])==False
  assert element_exists(0, [])==False
  assert element_exists(-1, [-2, -1, 0])==True
output: def element_exists(element, lst):
      return element in lst