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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 seek(self, offset, whence=0):
        '''
        Simple seek. Follows standard interface.
        '''
        if whence == 0:
            self._pos = self._start_pos + offset
        elif whence == 1:
            self._pos += offset
        else:
            self._pos = (self._end_pos - 1) + offset