validate that a value contains one or more space-delimited values

def _space_delimited_list(value):
    '''
    validate that a value contains one or more space-delimited values
    '''
    if isinstance(value, six.string_types):
        items = value.split(' ')
        valid = items and all(items)
    else:
        valid = hasattr(value, '__iter__') and (value != [])

    if valid:
        return True, 'space-delimited string'
    return False, '{0} is not a valid list.\n'.format(value)