code: def columnCount(self, index=QModelIndex()):
          
          # Avoid a "Qt exception in virtual methods" generated in our
          # tests on Windows/Python 3.7
          # See PR 8910
          try:
              # This is done to implement series
              if len(self.df.shape) == 1:
                  return 2
              elif self.total_cols <= self.cols_loaded:
                  return self.total_cols
              else:
                  return self.cols_loaded
          except AttributeError:
              return 0
docs: DataFrame column number