func (r region) Field(f string) region {
	finfo := r.typ.field(f)
	if finfo == nil {
		panic("can't find field " + r.typ.Name + "." + f)
	}
	return region{p: r.p, a: r.a.Add(finfo.Off), typ: finfo.Type}
}
func (r region) Field(f string) region {
	finfo := r.typ.field(f)
	if finfo == nil {
		panic("can't find field " + r.typ.Name + "." + f)
	}
	return region{p: r.p, a: r.a.Add(finfo.Off), typ: finfo.Type}
}
func ( r region ) Field ( f string ) region { finfo := r . typ . field ( f ) if finfo == nil { panic ( " " + r . typ . Name + " " + f ) } return region { p : r . p , a : r . a . Add ( finfo . Off ) , typ : finfo . Type } }
// Field returns the part of r which contains the field f.
// r must contain a struct, and f must be one of its fields.
Field returns the part of r which contains the field f . r must contain a struct and f must be one of its fields .