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1. The :mod:`mosql.util` is faster (1.35x~1.7x) after rewriting.
2. The :mod:`mosql.util` also supports to delimit the identifier (for avoiding
injection from identifier),
3. use arbitrary SQL statements by :class:`mosql.util.raw`,
4. and customize parameter name of prepared statement by
:class:`mosql.util.param` now.
5. The :mod:`mosql.ext` is deprecated now, please use :mod:`mosql.common`
instead.