Don’t get lost in words with tries!

The program searches a word puzzle for a preset of words, using prefix trees (tries) and backtracking depth-first search, in Pythonic Art.

python wordpuzzle.py
Added to Trie:  ['RASPBERRY', 'LIME', 'BLACKBERRY', 'BLUEBERRY', 'WATERMELON', 'ORANGE', 'BANANA', 'PAPAYA', 'LEMON', 'KIWI', 'STRAWBERRY', 'GRAPE', 'APPLE', 'POMEGRANATE', 'GUAVA']

 R  A  W  A  Y  R  Y  A  Y  A  P  A  P  B
 B  N  E  E  R  L  R  A  B  B  Y  E  E  L
 N  A  E  B  R  M  R  N  E  A  R  W  A  U
 B  N  S  A  E  P  E  R  N  N  R  A  I  E
 R  A  A  P  B  E  B  E  P  E  E  T  B  B
 S  B  L  B  K  E  P  O  E  A  B  E  N  E
 E  S  I  R  C  A  S  A  P  T  W  R  K  R
 E  Y  B  I  A  Y  A  E  E  E  A  M  L  R
 G  E  R  W  L  O  R  E  P  N  R  E  Y  Y
 N  P  R  I  B  B  N  M  L  T  T  L  M  M
 A  A  A  K  C  O  R  E  R  L  S  O  O  N
 R  R  A  R  M  A  E  L  I  M  E  N  E  C
 O  G  S  E  G  N  M  P  E  B  R  K  I  T
 S  P  L  A  E  E  L  P  P  A  B  E  W  I

Found:  ['RASPBERRY', 'LIME', 'BLACKBERRY', 'BLUEBERRY', 'WATERMELON', 'ORANGE', 'BANANA', 'PAPAYA', 'LEMON', 'KIWI', 'STRAWBERRY', 'GRAPE', 'APPLE']
Not Found:  ['POMEGRANATE', 'GUAVA']