<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _reverse_index(self):
 """ Move the cursor up one row in the same column. If the cursor is at the first row, create a new row at the top. """

        if self.y == 0:
            # If the cursor is currently at the first row, then scroll the
            # screen up.
            self.display = [u" " * self.size[1]] + self.display[:-1]
        else:
            # If the cursor is anywhere other than the first row than just move
            # it up by one row.
            self.y -= 1