How do I calculate the branch lengths

Question

[mdsiddra]

I'm using python 3.6 and I have utilized biopython package (https://biopython.org/) for drwaing phylogenetic tree with a newick format tree file. I want to calculate the branch lengths for the given tree file ('newick format'). What method should I use for this or if there is a python library with the method for calculating branch lengths from a tree file?

[Sej Modha]

I'd recommend using ETE toolkit for phylogenetic tree visualisation in python.

[mdsiddra]

This toolkit does not calculate the lengths of branches rather it just displays if they are already in the tree file. I need some methods of python or python library which can do so.