type ClauseBuilder func(Clause, Builder)

type Writer interface {
	WriteByte(byte) error
	WriteString(string) (int, error)
}

// Builder builder interface
type Builder interface {
	Writer
	WriteQuoted(field interface{})
	AddVar(Writer, ...interface{})
	AddError(error) error
}

// Clause
type Clause struct {
	Name                string // WHERE
	BeforeExpression    Expression