input: Write a python function to split a string by a given delimiter.
  assert split_string("hello,world", ",") == ["hello", "world"]
  assert split_string("apple|banana|cherry", "|") == ["apple", "banana", "cherry"]
  assert split_string("one-two-three", "-") == ["one", "two", "three"]
output: def split_string(s: str, delimiter: str) -> list:
      return s.split(delimiter)