get Changeset from Workteim

I have the following code (fragment):
```
client = TFSAPI(server_url=bh_tfs_base_url, project=collection, user=user, password=password, auth_type=HttpNtlmAuth)
px = client.run_query("Shared Queries/PX Queries/PX - Priority List")
for work_item in px.result.workitems:
change_sets_relation = work_item.find_in_relation("ArtifactLink")
for changeset_relation in change_sets_relation:
```
How to I create a Changetset object from the relation pointing to the changeset?