code: public boolean add(TemporalExtendedPropositionDefinition tepd) {
          if (tepd != null) {
              boolean result = this.abstractedFrom.add(tepd);
              if (result) {
                  recalculateChildren();
              }
              return result;
          } else {
              return false;
          }
      }
docs: Adds a proposition id from which this slice definition is abstracted.
  
  @param propId
  a proposition id <code>String</code> for an abstract
  parameter definition.