input: Write a function to convert a given string to a different case using the appropriate method. The function should take a string as input and return the string with its cases swapped.
  def convert_string_case(string):
      new_string = string.swapcase()
      return new_string
  
  assert convert_string_case("this Is A TeST") == "THIS iS a tEst"
  assert convert_string_case("Hello World") == "hELLO wORLD"
  assert convert_string_case("123!@#abc") == "123!@#ABC"
  assert convert_string_case("") == ""
  assert convert_string_case("ALL CAPS") == "all caps"
output: def convert_string_case(string):
      new_string = string.swapcase()
      return new_string