r""" Compare two sequences of lines; generate the delta as a context diff. Context diffs are a compact way of showing line changes and a few lines of context. The number of context lines is set by 'n' which defaults to three. By default, the diff control lines (those with ***
(a, b, fromfile='', tofile='',
fromfiledate='', tofiledate='', n=3, lineterm='\n')
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