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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 _index(self):
 """ Move the cursor down one row in the same column. If the cursor is at the last row, create a new row at the bottom. """


        if self.y + 1 >= self.size[0]:
            # If the cursor is currently on the last row, then spawn another
            # and scroll down (removing the top row).
            self.display = self.display[1:] + [u" " * self.size[1]]
        else:
            # If the cursor is anywhere else, then just move it to the 
            # next line.
            self.y += 1