code: def test_multiple_file_field(app, client):
      @app.post("/")
      @app.input(FilesList, location="files")
      def index(files_data):
          data = {"images": True}
          for f in files_data["images"]:
              if not isinstance(f, FileStorage):
                  data["images"] = False
          return data
  
      rv = client.post(
          "/",
          data={
              "images": [
                  (io.BytesIO(b"test0"), "test0.jpg"),
                  (io.BytesIO(b"test1"), "test1.jpg"),
                  (io.BytesIO(b"test2"), "test2.jpg"),
              ]
          },
          content_type="multipart/form-data",
      )
      assert rv.status_code == 200
      assert rv.json == {"images": True}
  
      rv = client.post(
          "/",
          data={
              "images": [
                  (io.BytesIO(b"test0"), "test0.jpg"),
                  (io.BytesIO(b"test1"), "test1.jpg"),
                  "test2",
              ]
          },
          content_type="multipart/form-data",
      )
      assert rv.status_code == 422
      assert rv.json["detail"]["files"]["images"]["2"] == [
          "Not a valid file."
      ]
  
file_path: apiflask/tests/test_fields.py
imports: import io
  import pytest
  from werkzeug.datastructures import FileStorage
  from .schemas import Files
  from .schemas import FilesList
  from apiflask import Schema
  from apiflask.fields import Config
label_desc: Use image node_id 2 for calling a global function with example usage: test_multiple_file_field(app, client) and returns: data