Bug on data_gen.py

[Joonyoung Yi]

First of all, thank you for putting this nice repository.
I really appreciate your effort to make this code.
I found a minor bug while I investigate your code for my own purpose.
There is a bug in the python file data_gen.py in 153-th line.
You would better change "if" to "elif". Thanks!

[Alexis Gidiotis]

@JoonyoungYi that is correct. It has been fixed. Thanks for the feedback.