docs: def sql_datetime_literal(dt: DateTimeLikeType,
                           subsecond: bool = False) -> str:
      """
      Transforms a Python object that is of duck type ``datetime.datetime`` into
      an ANSI SQL literal string, like ``'2000-12-31 23:59:59'``, or if
      ``subsecond=True``, into the (non-ANSI) format
      ``'2000-12-31 23:59:59.123456'`` or similar.
      """
      # ANSI SQL: http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt
      # <timestamp string>
      # ... the subsecond part is non-ANSI
      fmt = "'%Y-%m-%d %H:%M:%S{}'".format(".%f" if subsecond else "")
      return dt.strftime(fmt)