code: def check(config: "Config") -> None:
      """Check if revision command with autogenerate has pending upgrade ops.
  
      :param config: a :class:`.Config` object.
  
      .. versionadded:: 1.9.0
  
      """
  
      script_directory = ScriptDirectory.from_config(config)
  
      command_args = dict(
          message=None,
          autogenerate=True,
          sql=False,
          head="head",
          splice=False,
          branch_label=None,
          version_path=None,
          rev_id=None,
          depends_on=None,
      )
      revision_context = autogen.RevisionContext(
          config,
          script_directory,
          command_args,
      )
  
      def retrieve_migrations(rev, context):
          revision_context.run_autogenerate(rev, context)
          return []
  
      with EnvironmentContext(
          config,
          script_directory,
          fn=retrieve_migrations,
          as_sql=False,
          template_args=revision_context.template_args,
          revision_context=revision_context,
      ):
          script_directory.run_env()
  
      # the revision_context now has MigrationScript structure(s) present.
  
      migration_script = revision_context.generated_revisions[-1]
      diffs = []
      for upgrade_ops in migration_script.upgrade_ops_list:
          diffs.extend(upgrade_ops.as_diffs())
  
      if diffs:
          raise util.AutogenerateDiffsDetected(
              f"New upgrade operations detected: {diffs}"
          )
      else:
          config.print_stdout("No new upgrade operations detected.")
  
imports: from __future__ import annotations
  import os
  from typing import List
  from typing import Optional
  from typing import TYPE_CHECKING
  from typing import Union
  from .None import autogenerate
  from .None import util
  from .runtime.environment import EnvironmentContext
  from .script import ScriptDirectory
label_desc: Use image node_id 4 for calling a global function with example usage: check(config) and returns: list