If you want to replace different parts of a version, but leave other parts unmodified, use the function :meth:`~semver.version.Version.replace`:

>>> version = semver.Version.parse("1.4.5-pre.1+build.6")
>>> version.replace(major=2, minor=2)
Version(major=2, minor=2, patch=5, prerelease='pre.1', build='build.6')

If you pass invalid keys you get an exception:

>>> version = semver.Version.parse("1.4.5-pre.1+build.6")
>>> version.replace(invalidkey=2)
Traceback (most recent call last):
...
TypeError: replace() got 1 unexpected keyword argument(s): invalidkey