You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: observations_controller.rb
    path of file: ./repos/mushroom-observer/app/controllers/species_lists
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

#
#   :add_remove_observations
# Linked from observations :index and species_lists :show
# Form that sends all obs from current query to b
    
    def find_obs_query_or_redirect(spl = nil)
      query = find_query(:Observation)
      return query if query

      flash_error(:species_list_add_remove_no_query.t)
      if spl
        redirect_to(species_list_path(spl.id))
      else
        redirect_to(species_lists_path)
      end