diff --git a/go/vendor/golang.org/x/text/unicode/cldr/slice.go b/go/vendor/golang.org/x/text/unicode/cldr/slice.go
new file mode 100644
index 0000000..388c983
--- /dev/null
+++ b/go/vendor/golang.org/x/text/unicode/cldr/slice.go
@@ -0,0 +1,144 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cldr
+
+import (
+	"fmt"
+	"reflect"
+	"sort"
+)
+
+// Slice provides utilities for modifying slices of elements.
+// It can be wrapped around any slice of which the element type implements
+// interface Elem.
+type Slice struct {
+	ptr reflect.Value
+	typ reflect.Type
+}
+
+// Value returns the reflect.Value of the underlying slice.
+func (s *Slice) Value() reflect.Value {
+	return s.ptr.Elem()
+}
+
+// MakeSlice wraps a pointer to a slice of Elems.
+// It replaces the array pointed to by the slice so that subsequent modifications
+// do not alter the data in a CLDR type.
+// It panics if an incorrect type is passed.
+func MakeSlice(slicePtr interface{}) Slice {
+	ptr := reflect.ValueOf(slicePtr)
+	if ptr.Kind() != reflect.Ptr {
+		panic(fmt.Sprintf("MakeSlice: argument must be pointer to slice, found %v", ptr.Type()))
+	}
+	sl := ptr.Elem()
+	if sl.Kind() != reflect.Slice {
+		panic(fmt.Sprintf("MakeSlice: argument must point to a slice, found %v", sl.Type()))
+	}
+	intf := reflect.TypeOf((*Elem)(nil)).Elem()
+	if !sl.Type().Elem().Implements(intf) {
+		panic(fmt.Sprintf("MakeSlice: element type of slice (%v) does not implement Elem", sl.Type().Elem()))
+	}
+	nsl := reflect.MakeSlice(sl.Type(), sl.Len(), sl.Len())
+	reflect.Copy(nsl, sl)
+	sl.Set(nsl)
+	return Slice{
+		ptr: ptr,
+		typ: sl.Type().Elem().Elem(),
+	}
+}
+
+func (s Slice) indexForAttr(a string) []int {
+	for i := iter(reflect.Zero(s.typ)); !i.done(); i.next() {
+		if n, _ := xmlName(i.field()); n == a {
+			return i.index
+		}
+	}
+	panic(fmt.Sprintf("MakeSlice: no attribute %q for type %v", a, s.typ))
+}
+
+// Filter filters s to only include elements for which fn returns true.
+func (s Slice) Filter(fn func(e Elem) bool) {
+	k := 0
+	sl := s.Value()
+	for i := 0; i < sl.Len(); i++ {
+		vi := sl.Index(i)
+		if fn(vi.Interface().(Elem)) {
+			sl.Index(k).Set(vi)
+			k++
+		}
+	}
+	sl.Set(sl.Slice(0, k))
+}
+
+// Group finds elements in s for which fn returns the same value and groups
+// them in a new Slice.
+func (s Slice) Group(fn func(e Elem) string) []Slice {
+	m := make(map[string][]reflect.Value)
+	sl := s.Value()
+	for i := 0; i < sl.Len(); i++ {
+		vi := sl.Index(i)
+		key := fn(vi.Interface().(Elem))
+		m[key] = append(m[key], vi)
+	}
+	keys := []string{}
+	for k, _ := range m {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	res := []Slice{}
+	for _, k := range keys {
+		nsl := reflect.New(sl.Type())
+		nsl.Elem().Set(reflect.Append(nsl.Elem(), m[k]...))
+		res = append(res, MakeSlice(nsl.Interface()))
+	}
+	return res
+}
+
+// SelectAnyOf filters s to contain only elements for which attr matches
+// any of the values.
+func (s Slice) SelectAnyOf(attr string, values ...string) {
+	index := s.indexForAttr(attr)
+	s.Filter(func(e Elem) bool {
+		vf := reflect.ValueOf(e).Elem().FieldByIndex(index)
+		return in(values, vf.String())
+	})
+}
+
+// SelectOnePerGroup filters s to include at most one element e per group of
+// elements matching Key(attr), where e has an attribute a that matches any
+// the values in v.
+// If more than one element in a group matches a value in v preference
+// is given to the element that matches the first value in v.
+func (s Slice) SelectOnePerGroup(a string, v []string) {
+	index := s.indexForAttr(a)
+	grouped := s.Group(func(e Elem) string { return Key(e, a) })
+	sl := s.Value()
+	sl.Set(sl.Slice(0, 0))
+	for _, g := range grouped {
+		e := reflect.Value{}
+		found := len(v)
+		gsl := g.Value()
+		for i := 0; i < gsl.Len(); i++ {
+			vi := gsl.Index(i).Elem().FieldByIndex(index)
+			j := 0
+			for ; j < len(v) && v[j] != vi.String(); j++ {
+			}
+			if j < found {
+				found = j
+				e = gsl.Index(i)
+			}
+		}
+		if found < len(v) {
+			sl.Set(reflect.Append(sl, e))
+		}
+	}
+}
+
+// SelectDraft drops all elements from the list with a draft level smaller than d
+// and selects the highest draft level of the remaining.
+// This method assumes that the input CLDR is canonicalized.
+func (s Slice) SelectDraft(d Draft) {
+	s.SelectOnePerGroup("draft", drafts[len(drafts)-2-int(d):])
+}