code: def add_col(self, label):
          
          self.table.dataframe[label] = ''
          self.AppendCols(1, updateLabels=False)
          last_col = self.table.GetNumberCols() - 1
          self.SetColLabelValue(last_col, label)
          self.col_labels.append(label)
          self.size_grid()
          return last_col
docs: Update table dataframe, and append a new column
  
          Parameters
          ----------
          label : str
  
          Returns
          ---------
          last_col: int
              index column number of added col