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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 get_current_state_m(self):
 """Returns the state model of the currently open tab"""

        page_id = self.view.notebook.get_current_page()
        if page_id == -1:
            return None
        page = self.view.notebook.get_nth_page(page_id)
        state_identifier = self.get_state_identifier_for_page(page)
        return self.tabs[state_identifier]['state_m']