input: Write a function to search for any matches of a given input string within a list of strings using regular expressions. If a match is found, the function should return "String matches"; otherwise, it should return "String doesn't match".
  assert search_strings(["First", "Second", "Third"], "Second") == "String matches"
  assert search_strings(["First", "Second", "Third"], "Fourth") == "String doesn't match"
  assert search_strings(["First", "Second", "Third"], "rst") == "String matches"
  assert search_strings([], "First") == "String doesn't match"
  assert search_strings(["First", "Second", "Third"], "") == "String doesn't match"
output: def search_strings(string_list, input_string):
      import re
      for s in string_list:
          if re.search(input_string, s):
              return "String matches"
      return "String doesn't match"