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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 add_textbox(self, left, top, width, height):
 """Return newly added text box shape appended to this shape tree. The text box is of the specified size, located at the specified position on the slide. """

        sp = self._add_textbox_sp(left, top, width, height)
        self._recalculate_extents()
        return self._shape_factory(sp)