func (p *Path) Exists(context *Node) bool {
	return p.Iter(context).Next()
}
Exists returns whether any nodes match p on the given context.
package xmlpath
import (
	"fmt"
	"strconv"
	"unicode/utf8"
)
type Path struct {
	path  string
	steps []pathStep
}
func (p *Path) Iter(context *Node) *Iter {
	iter := Iter{
		make([]pathStepState, len(p.steps)),
		make([]bool, len(context.nodes)),
	}
	for i := range p.steps {
		iter.state[i].step = &p.steps[i]
	}
	iter.state[0].init(context)
	return &iter
}