input: Write a function to create an instance of the "sru" class and perform a search using its "search" method, passing in a query string and optionally a collection name, start record number, maximum number of records to return, and record schema. The function should return a "response" object containing the results of the search, or False if no results are found. Include assert statements to test the function with different inputs.
  
  
  assert search_sru("query_string", collection="ANP") != False
  assert search_sru("query_string", collection="DPO", startrecord=5, maximumrecords=10) != False
  assert search_sru("query_string", collection="BYVANCK", recordschema="dcx") != False
  assert search_sru("query_string", collection="SGD") != False
  assert search_sru("nonexistent_query_string", collection="GGC") == False
  
output: def search_sru(query_string, collection=None, startrecord=1, maximumrecords=10, recordschema=None):
      sru_instance = sru()
      response = sru_instance.search(query_string, collection=collection, startrecord=startrecord, maximumrecords=maximumrecords, recordschema=recordschema)
      if response:
          return response
      else:
          return False