// Splits the given []byte using the given regexp, then returns a slice
// containing a Feature constructed from each piece matched by the regexp
func getFeatures(b []byte, r *regexp.Regexp) []Feature {
words := r.FindAll(b, -1)
features := make([]Feature, len(words))
for i, w := range words {
features[i] = NewFeature(w)
}
return features
}