{"textDocument": {"uri": "file:///editCompletion.lean"},
 "position": {"line": 3, "character": 22}}
{"items":
 [{"label": "foo",
   "kind": 5,
   "data": ["file:///editCompletion.lean", 3, 22, 1, "cFoo.foo"]}],
 "isIncomplete": false}
Resolution of foo:
{"label": "foo",
 "kind": 5,
 "detail": "Foo → Nat",
 "data": ["file:///editCompletion.lean", 3, 22, 1, "cFoo.foo"]}