code: @Override
      public String parameters() {
          return Op.join(" ", vertexA, vertexB, vertexC, vertexD)
                  + (!Op.isEq(height, 1.0) ? " " + Op.str(height) : "");
      }
docs: Returns the parameters of the term
  
  @return `"vertexA vertexB vertexC vertexD [height]"`