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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _format_comments(ret, comments):
    '''
    DRY code for joining comments together and conditionally adding a period at
    the end, and adding this comment string to the state return dict.
    '''
    if isinstance(comments, six.string_types):
        ret['comment'] = comments
    else:
        ret['comment'] = '. '.join(comments)
        if len(comments) > 1:
            ret['comment'] += '.'
    return ret