Nutanix Python Developer interview questions

1st Techincal round - Write a binary tree program in python. Explain what are decorators, the difference between generator and iterators. 2nd Techincal round - Write a python program for Fibonacci - had to improve performance based on the increasing input. Program for n ^ m, had to improve performance based on increasing input as well. 3. F2F - Which they said I was shortlisted for and asked for my availability. I was not available the immediate week since I was traveling and offered for a Skype call. But, they insisted on F2F, for which I was available a week later. The HR kept telling me that she was working with the panel members on it, but after 3days I get an automated email saying the position has been filled.