code: func IN(binding ...interface{}) (exp Expression) {
  	bindingRefs := strings.Repeat(",?", len(binding))
  	return &PrefixedExp{" IN(", nil, bindingRefs[1:] + ")", binding}
  }
docs: // IN operator of SQL expression
  // 		FROM(UserTable,WHERE(FieldEQ(&UserTable.FirstName, IN(JamesBond.FirstName, PeterBond.FirstName)))