code: public OutputVariable removeOutputVariable(String name) {
          for (Iterator<OutputVariable> it = this.outputVariables.iterator(); it.hasNext();) {
              OutputVariable outputVariable = it.next();
              if (outputVariable.getName().equals(name)) {
                  it.remove();
                  return outputVariable;
              }
          }
          throw new RuntimeException(String.format(
                  "[engine error] no output variable by name <%s>", name));
      }
docs: Removes the output variable of the given name.
  
  @param name is the name of the output variable
  @return the output variable of the given name
  @throws RuntimeException if there is no variable with the given name