You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: zone.go
    path of file: ./repos/cockroach/pkg/config/zonepb
    
    the code of the file until where you have to start completion: // Copyright 2015 The Cockroach Authors.
//
// Use of
    
func (z ZoneConfig) SubzoneSplits() []roachpb.RKey {
	var out []roachpb.RKey
	for _, span := range z.SubzoneSpans {
		// TODO(benesch): avoid a split at the first partition's start key when it
		// is the minimum possible value.
		if len(out) == 0 || !out[len(out)-1].Equal(span.Key) {
			// Only split at the start key when it differs from the last end key.
			out = append(out, roachpb.RKey(span.Key))
		}
		endKey := span.EndKey
		if len(endKey) == 0 {
			endKey = span.Key.PrefixEnd()
		}
		out = append(out, roachpb.RKey(endKey))
		// TODO(benesch): avoid a split at the last partition's end key when it is
		// the maximum possible value.
	}
	return out
}