code: public static OpPredicate opNameEquals(final String opName){
          return new OpPredicate() {
              @Override
              public boolean matches(SameDiff sameDiff, DifferentialFunction function) {
                  return function.opName().equals(opName);
              }
          };
      }
docs: Return true if the operation name (i.e., "add", "mul", etc - not the user specified name) equals the specified name