Returns a list of string message of the differences in a diff dict.

    Each inner message is tabulated one tab deeper

def _get_changes_from_diff_dict(diff_dict):
    '''
    Returns a list of string message of the differences in a diff dict.

    Each inner message is tabulated one tab deeper
    '''
    changes_strings = []
    for p in diff_dict.keys():
        if not isinstance(diff_dict[p], dict):
            raise ValueError('Unexpected diff difct \'{0}\''.format(diff_dict))
        if sorted(diff_dict[p].keys()) == ['val1', 'val2']:
            # Some string formatting
            from_str = diff_dict[p]['val1']
            if isinstance(diff_dict[p]['val1'], six.string_types):
                from_str = '\'{0}\''.format(diff_dict[p]['val1'])
            elif isinstance(diff_dict[p]['val1'], list):
                from_str = '\'{0}\''.format(', '.join(diff_dict[p]['val1']))
            to_str = diff_dict[p]['val2']
            if isinstance(diff_dict[p]['val2'], six.string_types):
                to_str = '\'{0}\''.format(diff_dict[p]['val2'])
            elif isinstance(diff_dict[p]['val2'], list):
                to_str = '\'{0}\''.format(', '.join(diff_dict[p]['val2']))
            changes_strings.append('{0} from {1} to {2}'.format(
                p, from_str, to_str))
        else:
            sub_changes = _get_changes_from_diff_dict(diff_dict[p])
            if sub_changes:
                changes_strings.append('{0}:'.format(p))
                changes_strings.extend(['\t{0}'.format(c)
                                       for c in sub_changes])
    return changes_strings