Delete attributes from a given item in a domain.

        :type domain_or_name: string or :class:`boto.sdb.domain.Domain` object.
        :param domain_or_name: Either the name of a domain or a Domain object

        :type item_name: string
        :param item_name: The name of the item whose attributes are being
                          deleted.

        :type attributes: dict, list or :class:`boto.sdb.item.Item`
        :param attributes: Either a list containing attribute names which
                           will cause all values associated with that attribute
                           name to be deleted or a dict or Item containing the
                           attribute names and keys and list of values to
                           delete as the value.  If no value is supplied,
                           all attribute name/values for the item will be
                           deleted.
                           
        :type expected_value: list
        :param expected_value: If supplied, this is a list or tuple consisting
            of a single attribute name and expected value. The list can be 
            of the form:

                * ['name', 'value']

            In which case the call will first verify that the attribute "name" 
            of this item has a value of "value".  If it does, the delete
            will proceed, otherwise a ConditionalCheckFailed error will be 
            returned. The list can also be of the form:

                * ['name', True|False]

            which will simply check for the existence (True) or 
            non-existence (False) of the attribute.

        :rtype: bool
        :return: True if successful

def delete_attributes(self, domain_or_name, item_name, attr_names=None,
                          expected_value=None):
        """
        Delete attributes from a given item in a domain.

        :type domain_or_name: string or :class:`boto.sdb.domain.Domain` object.
        :param domain_or_name: Either the name of a domain or a Domain object

        :type item_name: string
        :param item_name: The name of the item whose attributes are being
                          deleted.

        :type attributes: dict, list or :class:`boto.sdb.item.Item`
        :param attributes: Either a list containing attribute names which
                           will cause all values associated with that attribute
                           name to be deleted or a dict or Item containing the
                           attribute names and keys and list of values to
                           delete as the value.  If no value is supplied,
                           all attribute name/values for the item will be
                           deleted.
                           
        :type expected_value: list
        :param expected_value: If supplied, this is a list or tuple consisting
            of a single attribute name and expected value. The list can be 
            of the form:

                * ['name', 'value']

            In which case the call will first verify that the attribute "name" 
            of this item has a value of "value".  If it does, the delete
            will proceed, otherwise a ConditionalCheckFailed error will be 
            returned. The list can also be of the form:

                * ['name', True|False]

            which will simply check for the existence (True) or 
            non-existence (False) of the attribute.

        :rtype: bool
        :return: True if successful
        """
        domain, domain_name = self.get_domain_and_name(domain_or_name)
        params = {'DomainName':domain_name,
                  'ItemName' : item_name}
        if attr_names:
            if isinstance(attr_names, list):
                self._build_name_list(params, attr_names)
            elif isinstance(attr_names, dict) or isinstance(attr_names, self.item_cls):
                self._build_name_value_list(params, attr_names)
        if expected_value:
            self._build_expected_value(params, expected_value)
        return self.get_status('DeleteAttributes', params)