'Emit a warning.
If *location* is given, it should either be a tuple of (docname, lineno)
or a string describing the location of the warning as well as possible.
*type* and *subtype* are used to suppress warnings with :confval:`suppress_warnings`.'

def warn(self, message, location=None, type=None, subtype=None):

    warnings.warn('app.warning()    is    now    deprecated.    Use    sphinx.util.logging    instead.', RemovedInSphinx20Warning)
    logger.warning(message, type=type, subtype=subtype, location=location)
