'Set URI of audio to be played.
You *MUST* call :meth:`prepare_change` before calling this method.
:param uri: the URI to play
:type uri: string'

def set_uri(self, uri):

    if (self.mixer is not None):
        current_volume = self.mixer.get_volume()
    else:
        current_volume = None
    self._pending_uri = uri
    self._pending_tags = {}
    self._playbin.set_property(u'uri', uri)
    if ((self.mixer is not None) and (current_volume is not None)):
        self.mixer.set_volume(current_volume)
