<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _pad_added(self, element, pad):
 """The callback for GstElement's "pad-added" signal. """

        # Decoded data is ready. Connect up the decoder, finally.
        name = pad.query_caps(None).to_string()
        if name.startswith('audio/x-raw'):
            nextpad = self.conv.get_static_pad('sink')
            if not nextpad.is_linked():
                self._got_a_pad = True
                pad.link(nextpad)