input: Write a function to search a given list of strings for any matches with the user's input string. The function should use regular expressions for the search and return "String matches" if a match is found, otherwise return "String doesn't match". The input list of strings should be provided as a parameter to the function.
  
  assert search_strings(["First", "Second", "Third"], "Sec")=="String matches"
  assert search_strings(["First", "Second", "Third"], "Fourth")=="String doesn't match"
  assert search_strings(["Apple", "Banana"], "an")=="String matches"
  assert search_strings(["Cat", "Dog"], "Horse")=="String doesn't match"
  assert search_strings(["Red", "Blue"], "Red")=="String matches"
output: import re
  
  def search_strings(string_list, user_input):
      for string in string_list:
          if re.search(user_input, string):
              return "String matches"
      return "String doesn't match"