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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 tab_insert(self, e):  # (M-TAB)
        u'''Insert a tab character. '''
        cursor = min(self.l_buffer.point, len(self.l_buffer.line_buffer))
        ws = ' ' * (self.tabstop - (cursor % self.tabstop))
        self.insert_text(ws)
        self.finalize()