There are 2 issues here:

* Technical: `_sqlite_*()` functions are locally defined at `peewee.py` and `pysqlcipher_ext` can't access them, but `SqlCipherDatabas` - as an instance of `SqliteDatabase` is allowed to call a private method it has *inherited* :relieved:
* Principal: `_add_conn_hooks()` may change tomorrow (when new hooks are introduced).
  It's better to do this in one place, so that all subclasses (e.g `SqlCipherDatabase`) stay compatible without a rewrite.