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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_from_seg(self, n):
 """Read from current seg. Args: n: max number of bytes to read. Returns: valid bytes from the current seg. "" if no more is left. """

    result = self._seg.read(size=n)
    if result == "":
      return result
    offset = self._seg.tell()
    if offset > self._seg_valid_length:
      extra = offset - self._seg_valid_length
      result = result[:-1*extra]
    self._offset += len(result)
    return result