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. The function should take two parameters: the element to search for and the list of integers.
  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('a', [1, 'a', 3, 4, 5])==True
  assert element_exists(3, [1, 2, 3, 4, 5])==True
  
output:     for item in list_int:
          if item == elem:
              return True
      return False