func (formatter *Formatter) Header() string {
	formatter.lock.Lock()
	defer formatter.lock.Unlock()
	return formatter.header
}
Header returns the header of the Formatter.
package text
import (
	"regexp"
	"strings"
	"sync"
	"github.com/gxlog/gxlog/iface"
)
var headerRegexp = regexp.MustCompile("{{([^:%]*?)(?::([^%]*?))?(%.*?)?}}")
type Formatter struct {
	header     string
	minBufSize int
	coloring   bool
	colorMgr  *colorMgr
	appenders []*headerAppender
	suffix    string
	lock sync.Mutex
}
func New(config Config) *Formatter {
	config.setDefaults()
	formatter := &Formatter{
		minBufSize: config.MinBufSize,
		coloring:   config.Coloring,
		colorMgr:   newColorMgr(),
	}
	formatter.SetHeader(config.Header)
	formatter.MapColors(config.ColorMap)
	return formatter
}