This line makes it appear that we actually want to parse most meta data from a vasprun.xml file (version, date, etc.), but this conditional is never hit because leaf.tag is never, e.g. 'generator'. I think the reason is probably because elementtree.iterparse seems to return xml elements depth first, i.e. leaf iterates over the tags inside <generator> but not that tag itself, but I don't have time to debug this in depth.