In shell, avoid editing text except between prompt and EOF

def restrict_cursor_position(self, position_from, position_to):
        """In shell, avoid editing text except between prompt and EOF"""
        position_from = self.get_position(position_from)
        position_to = self.get_position(position_to)
        cursor = self.textCursor()
        cursor_position = cursor.position()
        if cursor_position < position_from or cursor_position > position_to:
            self.set_cursor_position(position_to)