See changes that occured since last check in

def diff(context, file_name):
    """See changes that occured since last check in"""
    context.obj.find_repo_type()
    if context.obj.vc_name == 'git':
        context.obj.call(['git', 'diff', '--color-words',
                          '--ignore-space-change', file_name])
    elif context.obj.vc_name == 'hg':
        context.obj.call(['hg', 'diff', file_name])