{"textDocument": {"uri": "file://completion5.lean"},
 "position": {"line": 9, "character": 15}}
{"items":
 [{"label": "b1", "detail": "C → String"},
  {"label": "f1", "detail": "C → Nat"},
  {"label": "f2", "detail": "C → Bool"}],
 "isIncomplete": true}