'Attach an EBS volume to an EC2 instance.
:type volume_id: str
:param volume_id: The ID of the EBS volume to be attached.
:type instance_id: str
:param instance_id: The ID of the EC2 instance to which it will
be attached.
:type device: str
:param device: The device on the instance through which the
volume will be exposted (e.g. /dev/sdh)
:type dry_run: bool
:param dry_run: Set to True if the operation should not actually run.
:rtype: bool
:return: True if successful'

def attach_volume(self, volume_id, instance_id, device, dry_run=False):

    params = {'InstanceId': instance_id, 'VolumeId': volume_id, 'Device': device}
    if dry_run:
        params['DryRun'] = 'true'
    return self.get_status('AttachVolume', params, verb='POST')
