func (p *Param) Get(name string) *Param {
	if p == nil {
		return nil
	}
	if strings.EqualFold(p.Name, name) {
		return p
	}
	return p.Next.Get(name)
}
Get returns an entry in O(n) time.
package sip
import (
	"bytes"
	"strings"
)
type Param struct {
	Name  string
	Value string
	Next  *Param
}