The docstrings of both `assoc!` and `conj!` say "Returns coll.", possibly suggesting the transient edit happens (always) in-place, `coll` being the first argument. However, this is not the case and the returned collection should always be the one that's used.
Approach: Replace "Returns coll." with "Returns an updated collection." in `conj!`, `assoc!`, `pop!` docstrings.
Screened by: Alex Miller