Generic handler that will read all the data from an SSH or telnet channel.

def read_channel(self):
        """Generic handler that will read all the data from an SSH or telnet channel."""
        output = ""
        self._lock_netmiko_session()
        try:
            output = self._read_channel()
        finally:
            # Always unlock the SSH channel, even on exception.
            self._unlock_netmiko_session()
        return output