**Text generator, version 1:

    # Read text from a file, building a dictionary as we go
    #    each key is a word in the text; the value is the list
    #    of words that follow that word in the text.
    # Print random words, based on the dictionary.
    #    


Sample input text and the dictionary that is built for it:

Happy day and Happy year and sad minute.

{'': ['Happy'], 'and': ['Happy', 'sad'], 'minute.': [''], 
 'sad': ['minute.'], 'year': ['and'], 'day': ['and'], 
 'Happy': ['day', 'year']}



**Text generator, version 2:
    # Read text from a file, building a dictionary as we go
    #    Prefix is an integer. Suppose it is 2.  Then, we will
    #    keep track of the words that follow each pair of
    #    words in the text.  
    #    
    #    Each key is a tuple of words in the text; the value is the list
    #    of words that follow those words in the text.
    # Print random words, based on the dictionary.
    #    

Sample input text and the dictionary that is built for it:

Happy day and Happy day but Sad minute so Sad minute drats!

with prefix set at 2:

{('Happy', 'day'): ['and', 'but'], ('', 'Happy'): ['day'], 
 ('minute', 'so'): ['Sad'], ('Sad', 'minute'): ['so', 'drats!'], 
 ('day', 'and'): ['Happy'], ('minute', 'drats!'): [''], 
 ('', ''): ['Happy'], ('but', 'Sad'): ['minute'], 
 ('and', 'Happy'): ['day'], ('day', 'but'): ['Sad'], 
 ('so', 'Sad'): ['minute']}