// Good turing with a linear-combination fallback estimate
func JelinekMercer(counts, fallbackCounts gnlp.Counter, fallbackWeight func(key *string) float64, split func(key *string) (string, string)) {
counts.Apply(func(key *string, w float64) float64 {
_, smaller := split(key)
weight := fallbackWeight(key)
return (1-weight)*counts.Get(*key) + weight*fallbackCounts.Get(smaller)
})
counts.Normalize()
}
