'Declare the client application metadata supported.
Parameters
metadata : dict, optional
Dictionary containing the client application metadata as defined in
the SAMP definition document. If omitted, then no metadata are
declared.'

def declare_metadata(self, metadata=None):

    if (self.hub.is_connected and (self._private_key is not None)):
        if (metadata is not None):
            self._metadata.update(metadata)
        self.hub.declare_metadata(self._private_key, self._metadata)
    else:
        raise SAMPClientError(u'Unable    to    declare    metadata.    Hub    unreachable    or    not    connected    or    client    not    registered.')
