writeOuput method does not work.

[minsikseo-cdl]

Hi, I've written my custom ParOpt.Problem class:

class MyProb(ParOpt.Problem):
    def __init__(self, *args):
        # something ...
        # ...

    ....

    def writeOutput(self, iter, x):
        print(iter) # This is an example

as described in the document:

virtual void writeOutput(int iter, ParOptVec *x)¶
Implement this function if you'd like to print out something with the same frequency as the output files

But I cannot see anything on my terminal. I think my writeOutput method in MyProb does not work.
How can I monitor the optimization process in my own way?