from collections import defaultdict
#   You may use a regular dict in Python.
#   However, defaultdict allows you to:
#       [1] provide an appropriate initial default value to a key, and
#       [2] specify a data type of the value of a key so a default value can be provided.
#   This can simplify coding.

def create_jumble_words_file(input_file, output_file):
    # anagram_dict: a dictionary to store words grouped by their sorted character signature.
    #   The value of a key (signature) is a list of all word with the signature.
    #   For example, the signature of 'care' is 'acer'.
    #       The signatures of 'acre' and 'race' are also 'acer'.
    #       Those are the three words with the same signature 'acer'
    #   Eventually, at the end of the processing:
    #       anagram['acer'] has the value of ['acre', 'care', 'race']
    #   On the other hand, 'index' is the only word with the signature of 'deinx'.
    #   Thus, at the end of processing the input file,
    #       anagram_dict['deinx'] has the value of ['index']
    #
    #   Note that 'index' is a suitable word for the jumble game, 
    #   but not any of ['acre', 'care', 'race']
    anagram_dict = defaultdict(list)

    # [1] Read input and group words by sorted signature

    with open(input_file, 'r') as f:
        for line in f:
            #   Strip away possible spaces in the input word
            word = line.strip()
            #   Filter out/Skip words with three or less or eight or more characters and
            #   words with non-alphabets and 
            #   words with the first character in upper case.
            
            #   <<<Add your code here.>>>




            if word:
                # Signature: word characters sorted alphabetically
                signature =     #   <<<Add your code here.>>>
                
                
                
                
                #   Add the word to the list of the signature.
                #   Since we are using defaultdict, no need to 
                #   check whether the word is the first one in the
                #   signature.
                
                #   <<<Add your code here.>>>
                
                
                

    # [2] Keep only words that have no anagrams 
    #       (signature groups with exactly one word)
    #     Save these words in the list unique_words.
    # The list uniques should contain words that Jumble can use, one word per line.

    # <<<Add your code here.>>>
    
    
    

    # [3] Output the result (unique_words) to a new file, called jumble_words.txt
    
    # <<<Add your code here.>>>
    
    
    


# Usage
if __name__ == "__main__":
    create_jumble_words_file('words.txt', 'jumble_words.txt')
    #   Read the file 'words.txt' and output 'jumble_words.txt' for use in the Jumble game.