code: func Preparex(p Preparer, query string) (*Stmt, error) {
  	s, err := p.Prepare(query)
  	if err != nil {
  		return nil, err
  	}
  	return &Stmt{Stmt: s, unsafe: isUnsafe(p), Mapper: mapperFor(p)}, err
  }
docs: // Preparex prepares a statement.