<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def rewind(self, position=0):
 """Set the position of the data buffer cursor to 'position'."""

        if position < 0 or position > len(self._data):
            raise Exception("Invalid position to rewind cursor to: %s." % position)
        self._position = position