Counter({('the', 'quick'): 2, ('quick', 'person'): 2, ('person', 'did'): 1,
    ('did', 'not'): 1, ('not', 'realize'): 1, ('and', 'the'): 1, ('speed',
    'and'): 1, ('person', 'bumped'): 1, ('his', 'speed'): 1, ('realize',
    'his'): 1})
Counting bigrams (pair of two words) in a file using python