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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def trace_read(self, offset, num_items):
 """Reads data from the trace buffer and returns it. Args: self (JLink):
 the ``JLink`` instance. offset (int):
 the offset from which to start reading from the trace buffer. num_items (int):
 number of items to read from the trace buffer. Returns: A list of ``JLinkTraceData`` instances corresponding to the items read from the trace buffer. Note that this list may have size less than ``num_items`` in the event that there are not ``num_items`` items in the trace buffer. Raises: JLinkException: on error. """

        buf_size = ctypes.c_uint32(num_items)
        buf = (structs.JLinkTraceData * num_items)()
        res = self._dll.JLINKARM_TRACE_Read(buf, int(offset), ctypes.byref(buf_size))
        if (res == 1):
            raise errors.JLinkException('Failed to read from trace buffer.')
        return list(buf)[:int(buf_size.value)]