@classmethod
def ExternalDepFailed(cls, name, failmsg):
    """Inform that an optional dependency was not found.

        A new `_ExternalDep` object will be created and stored
        in `config`.

        :Parameters:
          name
            identifier of the optional dependency. This should
            be a valid python identifier, because it will be
            accessible as ``mdp.config.has_<name>`` attribute.
          failmsg
            an object convertible to ``str``, which will be displayed in
            ``mdp.config.info()`` output. This will usually be either an
            exception (e.g. ``ImportError``), or a message string.
        """
    return cls._ExternalDep(name, failmsg=failmsg)
