<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def sort_transcripts(self):
 """Sort the transcripts stored here"""

     txs = sorted(self.transcripts,key=lambda x: (x.range.chr, x.range.start, x.range.end))
     self._transcripts = txs