code: public void addArgsFor(SDVariable[] variables, DifferentialFunction function) {
          String[] varNames = new String[variables.length];
          for (int i = 0; i < varNames.length; i++) {
              if (variables[i] == null)
                  throw new ND4JIllegalStateException("Found null variable at index " + i);
              varNames[i] = variables[i].getVarName();
          }
          addArgsFor(varNames, function);
      }
docs: Adds incoming arguments for the specified differential function to the graph
  
  @param variables variables that are arguments (inputs) to the specified function
  @param function  Function