nd4j-backends/nd4j-api-parent/nd4j-api/src/main/java/org/nd4j/autodiff/samediff/SameDiff.java
public DifferentialFunction getFunctionById(String id) {
        if (!functionInstancesById.containsKey(id)) {
            throw new ND4JIllegalStateException("No function with id " + id + " found!");
        }
        return functionInstancesById.get(id);
    }
public DifferentialFunction getFunctionById(String id) {
        if (!functionInstancesById.containsKey(id)) {
            throw new ND4JIllegalStateException("No function with id " + id + " found!");
        }
        return functionInstancesById.get(id);
    }
Get the function by the {@link DifferentialFunction#getOwnName()}

@param id the id of the function
@return the function for the given id if it exists