<format> can be one of 'raw', 'medium', 'short', 'full',
and 'oneline'.
+-m::
+ By default, differences for merge commits are not shown.
+ With this flag, show differences to that commit from all
+ of its parents.
+
+ However, it is not very useful in general, although it
+ *is* useful on a file-by-file basis.
Author
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