docs: public void putSubFunction(String name, SameDiff nameSpace) {
          if (sameDiffFunctionInstances.containsKey(name) && sameDiffFunctionInstances.get(name) != nameSpace) {
              throw new ND4JIllegalStateException("Unable to replace samediff namespace. Please choose another opName");
          }
  
          sameDiffFunctionInstances.put(name, nameSpace);
      }