<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def mysummary(self):
 """Display a summary of the IGMPv3 object."""


    if isinstance(self.underlayer, IP):
      return self.underlayer.sprintf("IGMPv3: %IP.src% > %IP.dst% %IGMPv3.type% %IGMPv3.gaddr%")
    else:
      return self.sprintf("IGMPv3 %IGMPv3.type% %IGMPv3.gaddr%")