in templates/vm_multiple_instances.py [0:0]
def AddDisksToContext(context, new_disks):
"""Makes the context aware of the disks that need to be created."""
# This method will modify properties if needed.
prop = context.properties
if new_disks:
disk_resources = prop.setdefault(default.DISK_RESOURCES, list())
disk_resources.extend(new_disks)