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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 setup_columns(self):
 """Creates the treeview stuff"""

        tv = self.view['tv_categories']

        # sets the model
        tv.set_model(self.model)
        
        # creates the columns
        cell = gtk.CellRendererText()
        tvcol = gtk.TreeViewColumn('Name', cell)

        def cell_data_func(col, cell, mod, it):
            if mod[it][0]: cell.set_property('text', mod[it][0].name)
            return
        tvcol.set_cell_data_func(cell, cell_data_func)
        
        tv.append_column(tvcol)                
        return