code: def column_signs_(self):
          
          if self._always_positive():
              return np.ones(self.n_features)
          self.unhasher.recalculate_attributes()
          return self.unhasher.column_signs_
docs: Return a numpy array with expected signs of features.
          Values are
  
          * +1 when all known terms which map to the column have positive sign;
          * -1 when all known terms which map to the column have negative sign;
          * ``nan`` when there are both positive and negative known terms
            for this column, or when there is no known term which maps to this
            column.