diff --git a/dev/examples/sandman.txt b/dev/examples/sandman.txt
new file mode 100644
index 0000000..d9cc0a2
--- /dev/null
+++ b/dev/examples/sandman.txt
@@ -0,0 +1,26 @@
+Mister Sandman, bring me a dream
+Make him the cutest that I've ever seen
+Give him two lips like roses in clover
+Then tell him that his lonesome nights are over
+Sandman, I'm so alone
+Don't have nobody to call my own
+Please turn on your magic beam
+Mister Sandman, bring me a dream
+Mister Sandman, bring me a dream
+Make him the cutest that I've ever seen
+Give him the word that I'm not a rover
+Then tell him that his lonesome nights are over
+Mister Sandman, I'm so alone
+Don't have nobody to call my own
+Please turn on your magic beam
+Mister Sandman, bring me a dream
+Mister Sandman, (yeesss?) bring us a dream
+Give him a pair of eyes with a come-hither gleam
+Give him a lonely heart like Pagliacci
+And lots of wavy hair like Liberace
+Mister Sandman, someone to hold
+Would be so peachy before we're too old
+So please turn on your magic beam
+Mister Sandman, bring us
+Please, please, please
+Mister Sandman, bring us a dream
diff --git a/dev/examples/scratch.clj b/dev/examples/scratch.clj
new file mode 100644
index 0000000..b6ce98f
--- /dev/null
+++ b/dev/examples/scratch.clj
@@ -0,0 +1,407 @@
+(ns examples.scratch
+  (:require [clojure.java.io :as io]
+            [clojure.string :as string]
+            [clojure.set]
+            [com.owoga.prhyme.nlp.core :as nlp]))
+
+(def re-word
+  "Regex for tokenizing a string into words
+  (including contractions and hyphenations),
+  commas, periods, and newlines."
+  #"(?s).*?([a-zA-Z\d]+(?:['\-]?[a-zA-Z]+)?|,|\.|\n)")
+
+(defn tokenize
+  "Tokenizes for suffix trie. First token is end of document."
+  [text]
+  (->> text
+       (re-seq re-word)
+       (map second)
+       (map string/lower-case)
+       (reverse)
+       (cons :end)))
+
+(comment
+  (-> (slurp "dev/examples/sandman.txt")
+      tokenize))
+
+(defn zero-to-n-seq
+  ([coll]
+   (zero-to-n-seq coll 1))
+  ([coll i]
+   (let [l (count coll)]
+     (if
+         (> i l) nil
+         (cons (take i coll)
+               (lazy-seq (zero-to-n-seq coll (inc i))))))))
+(comment
+  (zero-to-n-seq '(1 2 3 4))
+  ;; => ((1) (1 2) (1 2 3) (1 2 3 4))
+  )
+
+(defn i-to-j-seq
+  ([coll i j]
+   (zero-to-n-seq (->> coll (drop i) (take (- j i))))))
+
+(defn n-to-zero-seq
+  ([coll]
+   (n-to-zero-seq coll 0))
+  ([coll i]
+   (if (= i (count coll)) nil
+       (cons (drop i coll)
+             (lazy-seq (n-to-zero-seq coll (inc i)))))))
+(comment
+  (n-to-zero-seq '(1 2 3 4))
+  ;; => ((1 2 3 4) (2 3 4) (3 4) (4))
+  )
+
+(defn add-to-trie [trie coll]
+  (update-in trie (concat coll [:count]) (fnil inc 0)))
+
+(defn add-multiple-to-trie [trie colls]
+  (loop [colls colls
+         trie trie]
+    (cond
+      (empty? colls) trie
+      :else (recur (rest colls)
+             (add-to-trie trie (first colls))))))
+
+(defn n-gram-suffix-trie
+  "Creates a suffix trie of 1-gram to n-gram.
+  Useful for backoff language model (I think)."
+  [n tokens]
+  (let [trie {}
+        windows (partition (inc n) 1 tokens)]
+    (loop [trie trie
+           windows windows]
+      (cond
+        (= 1 (count windows))
+        (add-multiple-to-trie
+         trie
+         (concat (zero-to-n-seq (first windows))
+                 (rest (n-to-zero-seq (first windows)))))
+        :else
+        (recur (add-multiple-to-trie
+                trie
+                (zero-to-n-seq (first windows)))
+               (rest windows))))))
+
+(comment
+  (let [last-window '("in" "the" "frat")]
+    (concat (zero-to-n-seq last-window)
+            (rest (n-to-zero-seq last-window))))
+  ;; => (("in") ("in" "the") ("in" "the" "frat") ("the" "frat") ("frat"))
+
+  (n-gram-suffix-trie
+   2
+   (string/split
+    "the cat in the hat is the rat in the frat"
+    #" "))
+  ;; => {"the"
+  ;;     {:count 3,
+  ;;      "cat" {:count 1, "in" {:count 1}},
+  ;;      "hat" {:count 1, "is" {:count 1}},
+  ;;      "rat" {:count 1, "in" {:count 1}},
+  ;;      "frat" {:count 1}},
+  ;;     "cat" {:count 1, "in" {:count 1, "the" {:count 1}}},
+  ;;     "in" {:count 2, "the" {:count 2, "hat" {:count 1}, "frat" {:count 1}}},
+  ;;     "hat" {:count 1, "is" {:count 1, "the" {:count 1}}},
+  ;;     "is" {:count 1, "the" {:count 1, "rat" {:count 1}}},
+  ;;     "rat" {:count 1, "in" {:count 1, "the" {:count 1}}},
+  ;;     "frat" {:count 1}}
+  )
+
+(comment
+  (def unigram
+    (n-gram-suffix-trie
+     1
+     (tokenize (slurp "dev/examples/sandman.txt"))))
+
+  unigram
+  (->> unigram
+       (map (fn [[k v]] (vector k (:count v))))
+       (map second)
+       (apply +))
+
+  (def bigram
+    (n-gram-suffix-trie
+     2
+     (tokenize (slurp "dev/examples/sandman.txt"))))
+
+  (->> bigram
+       (map (fn [[k v]] (vector k (:count v))))
+       (map second)
+       (apply +))
+
+  (count bigram)
+  (->> bigram
+       (take 4)
+       (into {}))
+  ;; => {"cutest" {:count 2, "the" {:count 2, "him" {:count 2}}},
+  ;;     "us" {:count 3, "bring" {:count 3, "," {:count 2}, "yeesss" {:count 1}}},
+  ;;     "his" {:count 2, "that" {:count 2, "him" {:count 2}}},
+  ;;     "him"
+  ;;     {:count 8,
+  ;;      "give" {:count 4, "\n" {:count 4}},
+  ;;      "tell" {:count 2, "then" {:count 2}},
+  ;;      "make" {:count 2, "\n" {:count 2}}}}
+  (->> bigram
+       vals
+       (map :count)
+       frequencies
+       (into [])
+       sort
+       (map #(apply * %))
+       (apply +))
+  (count (tokenize (slurp "dev/examples/sandman.txt")))
+  ;; => ([1 32] [2 20] [3 10] [4 3] [5 1] [6 2] [7 1] [8 2] [9 1] [10 1] [12 1] [26 1])
+  )
+
+
+
+(defn P [trie w]
+  (let [ws (trie w)
+        c (get-in trie [w :count])]
+    (->> ws
+         (#(dissoc % :count))
+         (map
+          (fn [[k v]]
+            [k (/ (:count v) c)])))))
+
+(defn vals-or-seconds [m]
+  (cond
+    (empty? m) m
+    (map? m) (apply concat (vals m))
+    :else (apply concat (map second m))))
+
+(defn flat-at-depth
+  "Convenience way of getting frequencies of n-grams.
+  Given a trie with a depth of 0, it will return all 1-grams key/value pairs.
+  That collection can be filtered for keys that hold the freqs."
+  [m depth]
+  (let [m (if (map? m) (into [] m) m)]
+    (cond
+      (<= depth 0) m
+      :else (flat-at-depth (->> m (mapcat second) (remove #(= :count (first %))))
+                           (dec depth)))))
+
+(comment
+  (let [trie {"d" {:count 3
+                   "o" {:count 3
+                        "g" {:count 2}
+                        "t" {:count 1}}
+                   "a" {:count 1
+                        "y" {:count 1}}}
+              "f" {:count 2
+                   "o" {:count 1
+                        "g" {:count 1}}
+                   "i" {:count 1
+                        "g" {:count 1}}}}]
+    (->> (flat-at-depth trie 2)))
+  )
+
+
+;; Let Nc be the number of N-grams that occur c times.
+;; Good-turing discounting:
+;; c* = (c + 1) * Nc+1 / Nc
+
+(defn n-gram-frequencies [trie n]
+  (if (< n 0)
+    {}
+    (->> trie
+         (#(flat-at-depth % (dec n)))
+         (map second)
+         (map :count)
+         frequencies
+         (into (sorted-map)))))
+
+(defn n-gram->occurence-count-frequencies [trie n]
+  (n-gram-frequencies trie n))
+
+(comment
+  (def tokens ["d" "o" "g" "\n" "d" "a" "y" "\n" "d" "o" "g" "\n" "d" "o" "t"])
+  (def trie (n-gram-suffix-trie 2 tokens))
+  trie
+  ;; => {"d"
+  ;;     {:count 4,
+  ;;      "o" {:count 3, "g" {:count 2}, "t" {:count 1}},
+  ;;      "a" {:count 1, "y" {:count 1}}},
+  ;;     "o" {:count 2, "g" {:count 2, "\n" {:count 2}}},
+  ;;     "g" {:count 2, "\n" {:count 2, "d" {:count 2}}},
+  ;;     "\n" {:count 3, "d" {:count 3, "a" {:count 1}, "o" {:count 2}}},
+  ;;     "a" {:count 1, "y" {:count 1, "\n" {:count 1}}},
+  ;;     "y" {:count 1, "\n" {:count 1, "d" {:count 1}}}}
+
+  (count bigram)
+  (count (flat-at-depth bigram 0))
+  (->> bigram
+       (#(flat-at-depth % 0))
+       (filter #(= :count (first %)))
+       (map second)
+       frequencies
+       (into (sorted-map))
+       (map #(apply * %))
+       (apply +))
+
+  (n-gram-frequencies trie 2)
+  ;; => {3 2, 1 3, 2 2}
+  ;; for bigrams
+  ;; of frequency 3 occurs 2 times
+  ;; of frequency 2 occurs 2 times
+  ;; of frequency 1 occurs 3 times
+
+  (n-gram-frequencies trie 1)
+  ;; => {4 1, 2 2, 3 1, 1 2}
+
+  )
+
+(defn num-seen-n-grams [trie n]
+  (->> trie
+       (#(flat-at-depth % (dec n)))
+       (remove #(= :count (first %)))
+       count))
+
+(defn n-gram-frequency-map
+  "Map of n-gram to frequency of frequencies."
+  [trie n]
+  (into
+   {}
+   (map
+    #(vector % (n-gram-frequencies trie %))
+    (range 1 (inc n)))))
+
+(comment
+  (n-gram-frequencies bigram 1)
+
+  (n-gram-frequency-map bigram 2)
+
+  )
+
+(defn number-of-n-grams [trie n]
+  (->> trie
+       (#(flat-at-depth % (dec n)))
+       (remove #(= :count (first %)))
+       count))
+
+(defn number-of-possible-n-grams [dict n]
+  (int (Math/pow (count dict) n)))
+
+(defn number-of-n-grams-that-occur-c-times [trie n c]
+  (if (zero? c)
+    (- (number-of-possible-n-grams trie n)
+       (count (flat-at-depth trie (dec n))))
+    (let [frequencies-map (->> (n-gram-frequency-map trie n)
+                               (#(get % n)))]
+      (get frequencies-map c 0))))
+
+(comment
+  (number-of-possible-n-grams bigram 2)
+  (count (flat-at-depth bigram 1))
+  (count bigram)
+  (->> (number-of-n-grams-that-occur-c-times bigram 1 1))
+ 
+  (->> (number-of-n-grams-that-occur-c-times bigram 0 3)
+       (filter #(= :count (first %)))
+       (map second)
+       frequencies
+       sort)
+  )
+
+(defn mle [trie c]
+  (let [N (->> trie vals (map :count) (apply +))]
+    (/ c N)))
+
+(->> bigram
+     (filter (fn [[k v]] (= 3 (v :count)))))
+
+(defn turings-estimate [trie n r]
+  (/ (* (inc r)
+        (number-of-n-grams-that-occur-c-times trie n (inc r)))
+     (number-of-n-grams-that-occur-c-times trie n r)))
+
+(defn good-turing [trie n r]
+  (let [nr (number-of-n-grams-that-occur-c-times trie n r)
+        nr1 (number-of-n-grams-that-occur-c-times trie n (inc r))]
+    (println
+     (format "cx %d nc %d ncx1 %d - %f"
+             r nr nr1 (float (/ (* (inc r) nr1) nr))))
+    (/ (* (inc r) nr1) nr)))
+
+(comment
+  (number-of-n-grams-that-occur-c-times bigram 1 1)
+  ;; unigram counts
+  (def unigram-counts
+    (->> bigram
+         vals
+         (map :count)
+         frequencies
+         (into (sorted-map))))
+  ;; => {1 32, 2 20, 3 10, 4 3, 5 1, 6 2, 7 1, 8 1, 9 1, 10 2, 12 1, 26 1}
+  ;; revised good-turing counts
+  (->> unigram-counts
+       (map
+        (fn [[freq freq']]
+          [freq (good-turing bigram 1 freq)]))
+       (into (sorted-map)))
+  ;; => {1 5/4, 2 3/2, 3 6/5, 4 5/3, 5 12, 6 7/2, 7 8, 8 9, 9 20, 10 0, 12 0, 26 0}
+  (map (fn [[r nr]]
+         (good-turing bigram 1 r))
+       unigram-counts)
+
+  ;; => (5/4 3/2 6/5 5/3 12 7/2 8 9 20 0 0 0)
+  (turings-estimate bigram 1 7)
+  )
+
+(defn revise-frequencies [frequencies N]
+  (let [m (reverse (sort (keys frequencies)))]
+    (loop [revised {}
+           m m]
+      (cond
+        (empty? m) revised
+        :else
+        (recur
+         (assoc
+          revised
+          (first m)
+          (good-turing (get frequencies (first m) 0)
+                       (get frequencies (second m) 0)
+                       N))
+         (rest m))))))
+
+(comment
+  (get (n-gram-frequency-map trie 3) 1)
+  ;; => {4 1, 2 2, 3 1, 1 2}
+  (revise-frequencies
+   (get (n-gram-frequency-map trie 3) 1)
+   (apply + (map :count (vals trie))))
+  ;; => {4 2/13, 3 4/13, 2 3/13, 1 0}
+
+  (def n-gram-freq-map (n-gram-frequency-map trie 3))
+  (def unigram-frequencies (n-gram-freq-map 1))
+  unigram-frequencies
+
+  )
+
+(defn number-of-n-grams-that-occur-with-count [trie n c]
+  )
+(defn good-turing-discount [trie c]
+  )
+
+(->> bigram
+     (map second))
+(count (into #{} (tokenize (slurp "dev/examples/sandman.txt"))))
+(->> bigram
+     (map second)
+     (map #(dissoc % :count))
+     (map keys)
+     flatten
+     (into #{})
+     (clojure.set/difference (into #{} (keys bigram))))
+
+(partition 3 1 (repeat :end) (range 6))
+
+(let [documents (->> "dark-corpus"
+                     io/file
+                     file-seq
+                     (remove #(.isDirectory %))
+                     (take 10))]
+  documents)