func (stream *Stream) Buffer() []byte {
	return stream.buf
}
Buffer if writer is nil, use this method to take the result
package jsoniter
import (
	"io"
)
type Stream struct {
	cfg        *frozenConfig
	out        io.Writer
	buf        []byte
	Error      error
	indention  int
	Attachment interface{}  
}
func NewStream(cfg API, out io.Writer, bufSize int) *Stream {
	return &Stream{
		cfg:       cfg.(*frozenConfig),
		out:       out,
		buf:       make([]byte, 0, bufSize),
		Error:     nil,
		indention: 0,
	}
}
func (stream *Stream) Pool() StreamPool {
	return stream.cfg
}
func (stream *Stream) Reset(out io.Writer) {
	stream.out = out
	stream.buf = stream.buf[:0]
}
func (stream *Stream) Available() int {
	return cap(stream.buf) - len(stream.buf)
}
func (stream *Stream) Buffered() int {
	return len(stream.buf)
}