class_docstr: Fake message returned by pygrib.open().message(x).
class_docstr_tok: ["Fake","message","returned","by","pygrib.open","(",")",".message","(","x",")","."]
docstr: Check if key is valid.
docstr_tok: ["Check","if","key","is","valid","."]
code: def valid_key(self, key):
      """Check if key is valid."""
      return True
  
imports: import sys
  import unittest
  from datetime import datetime
  from unittest import mock
  import numpy
  from pytest import approx
  from satpy.tests.utils import make_dataid
label_desc: Use image node_id 4 for calling the FakeMessage obj's underlying member method code with example usage: obj.valid_key(key) and returns: True