input: Write a function to add and remove elements from a global list and verify its contents using assert statements.
  assert int_list == []
  add_element_to_list(5)
  assert int_list == [5]
  add_element_to_list(10)
  assert int_list == [5, 10]
  remove_element_from_list(5)
  assert int_list == [10]
  remove_element_from_list(10)
  assert int_list == []
output: int_list = []
  
  def add_element_to_list(element):
      global int_list
      int_list.append(element)
  
  def remove_element_from_list(element):
      global int_list
      int_list.remove(element)