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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 read(self, length, timeout=None):
 """Read up to `length` number of bytes from the serial port with an optional timeout. `timeout` can be positive for a timeout in seconds, 0 for a non-blocking read, or negative or None for a blocking read that will block until `length` number of bytes are read. Default is a blocking read. For a non-blocking or timeout-bound read, read() may return data whose length is less than or equal to the requested length. Args: length (int):
 length in bytes. timeout (int, float, None):
 timeout duration in seconds. Returns: bytes: data read. Raises: SerialError: if an I/O or OS error occurs. """

        data = b""

        # Read length bytes if timeout is None

        # Read up to length bytes if timeout is not None
        while True:
            if timeout is not None:
                # Select
                (rlist, _, _) = select.select([self._fd], [], [], timeout)
                # If timeout
                if self._fd not in rlist:
                    break

            try:
                data += os.read(self._fd, length - len(data))
            except OSError as e:
                raise SerialError(e.errno, "Reading serial port: " + e.strerror)

            if len(data) == length:
                break

        return data