input: Write a function named `search_string` that takes a list of strings and a user input string as arguments. The function should search the list of strings to find if any of them match the user input string. If a match is found, the function returns "String matches". If no match is found, the function returns "String doesn't matches". If the list of strings is empty, the function should return "No strings to search".
  assert search_string(["First", "Second", "Third"], "Second") == "String matches"
  assert search_string(["First", "Second", "Third"], "Fourth") == "String doesn't matches"
  assert search_string(["First", "Second", "Third"], "trd") == "String matches"
  assert search_string(["First", "Second", "Third"], "") == "String doesn't matches"
  assert search_string([], "Second") == "No strings to search"
output: def search_string(strings, user_input):
      if not strings:
          return "No strings to search"
      for s in strings:
          if user_input in s:
              return "String matches"
      return "String doesn't matches"