code: def _add_query_parameter(url, name, value):
      
      if value is None:
          return url
      else:
          return update_query_params(url, {name: value})
docs: Adds a query parameter to a url.
  
      Replaces the current value if it already exists in the URL.
  
      Args:
          url: string, url to add the query parameter to.
          name: string, query parameter name.
          value: string, query parameter value.
  
      Returns:
          Updated query parameter. Does not update the url if value is None.