text: from typing import Optional
  
  from fastapi import FastAPI, Query
  
  app = FastAPI()
  
  
  @app.get("/items/")
  async def read_items(
      q: Optional[str] = Query(None, min_length=3, max_length=50, regex="^fixedquery$")
  ):
      results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
      if q:
          results.update({"q": q})
      return results
  