code: def resolve_config_spec(config_spec, config_dir=''):
      
      if '/' in config_spec or config_spec.endswith('.yml'):
          return config_spec
      return os.path.join(config_dir, '%s.yml' % config_spec)
docs: Resolves :attr:`config_spec` to a path to a config file.
  
      :param str config_spec:  Valid config specs:
  
          - The basename of a YAML config file *without* the ``.yml`` extension.
            The full path to the config file is resolved by appending ``.yml`` to
            the basename, then by searching for the result in the
            :attr:`config_dir`.
  
          - The path to a YAML config file.  The path may be absolute or may be
            relative to the current working directory.  If :attr:`config_spec`
            contains a ``/`` (forward slash), or if it ends in ``.yml``, it is
            treated as a path.
  
      :param str config_dir:  The directory in which to search for stack
          configuration files.
  
      :rtype:  :class:`str`