'Formats a single attribute line.'

def list_attribute(self, crop, attr, value):

    if crop:
        if (not isinstance(value, basestring)):
            value = utils.to_str(value, force_string=True)
        value = utils.crop(value)
        value = utils.to_unicode(value)
    string = ('\n    %s    =    %s' % (attr, value))
    string = raw(string)
    return string
