Returns a string of the installed licenses the J-Link has.

        Args:
          self (JLink): the ``JLink`` instance

        Returns:
          String of the contents of the custom licenses the J-Link has.

def custom_licenses(self):
        """Returns a string of the installed licenses the J-Link has.

        Args:
          self (JLink): the ``JLink`` instance

        Returns:
          String of the contents of the custom licenses the J-Link has.
        """
        buf = (ctypes.c_char * self.MAX_BUF_SIZE)()
        result = self._dll.JLINK_EMU_GetLicenses(buf, self.MAX_BUF_SIZE)
        if result < 0:
            raise errors.JLinkException(result)
        return ctypes.string_at(buf).decode()