func IsReaderError(err error) bool {
	return errors.IsError(err, ErrBuilder)
}
IsReaderError checks for an error during SML text reading.
package sml
import (
	"github.com/tideland/golib/errors"
)
const (
	ErrBuilder = iota + 1
	ErrReader
	ErrNoRootProcessor
	ErrRegisteredPlugin
)
var errorMessages = errors.Messages{
	ErrBuilder:          "cannot build node structure: %v",
	ErrReader:           "cannot read SML document: %v",
	ErrNoRootProcessor:  "no root processor registered",
	ErrRegisteredPlugin: "plugin processor with tag %q is already registered",
}
func IsBuilderError(err error) bool {
	return errors.IsError(err, ErrBuilder)
}