<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _sslobj(sock):
 """Returns the underlying PySLLSocket object with which the C extension functions interface. """

    pass
    if isinstance(sock._sslobj, _ssl._SSLSocket):
        return sock._sslobj
    else:
        return sock._sslobj._sslobj