Retrieve all the instances associated with your account.

        :type instance_ids: list
        :param instance_ids: A list of strings of instance IDs

        :type filters: dict
        :param filters: Optional filters that can be used to limit
                        the results returned.  Filters are provided
                        in the form of a dictionary consisting of
                        filter names as the key and filter values
                        as the value.  The set of allowable filter
                        names/values is dependent on the request
                        being performed.  Check the EC2 API guide
                        for details.

        :rtype: list
        :return: A list of  :class:`boto.ec2.instance.Reservation`

def get_all_instances(self, instance_ids=None, filters=None):
        """
        Retrieve all the instances associated with your account.

        :type instance_ids: list
        :param instance_ids: A list of strings of instance IDs

        :type filters: dict
        :param filters: Optional filters that can be used to limit
                        the results returned.  Filters are provided
                        in the form of a dictionary consisting of
                        filter names as the key and filter values
                        as the value.  The set of allowable filter
                        names/values is dependent on the request
                        being performed.  Check the EC2 API guide
                        for details.

        :rtype: list
        :return: A list of  :class:`boto.ec2.instance.Reservation`
        """
        params = {}
        if instance_ids:
            self.build_list_params(params, instance_ids, 'InstanceId')
        if filters:
            if 'group-id' in filters:
                gid = filters.get('group-id')
                if not gid.startswith('sg-') or len(gid) != 11:
                    warnings.warn(
                        "The group-id filter now requires a security group "
                        "identifier (sg-*) instead of a group name. To filter "
                        "by group name use the 'group-name' filter instead.",
                        UserWarning)
            self.build_filter_params(params, filters)
        return self.get_list('DescribeInstances', params,
                             [('item', Reservation)], verb='POST')