code: def register_code_directive():
      
      if not SPHINX_INSTALLED:
          docutils.parsers.rst.directives.register_directive('code',
                                                             CodeBlockDirective)
          docutils.parsers.rst.directives.register_directive('code-block',
                                                             CodeBlockDirective)
          docutils.parsers.rst.directives.register_directive('sourcecode',
                                                             CodeBlockDirective)
docs: Register code directive.