<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def swo_read_stimulus(self, port, num_bytes):
 """Reads the printable data via SWO. This method reads SWO for one stimulus port, which is all printable data. Note: Stimulus port ``0`` is used for ``printf`` debugging. Args: self (JLink):
 the ``JLink`` instance port (int):
 the stimulus port to read from, ``0 - 31`` num_bytes (int):
 number of bytes to read Returns: A list of bytes read via SWO. Raises: ValueError: if ``port < 0`` or ``port > 31`` """

        if port < 0 or port > 31:
            raise ValueError('Invalid port number: %s' % port)

        buf_size = num_bytes
        buf = (ctypes.c_uint8 * buf_size)()
        bytes_read = self._dll.JLINKARM_SWO_ReadStimulus(port, buf, buf_size)

        return list(buf)[:bytes_read]