This class has the same behavior than the containing class: it implements the advance operation in paginated collections. Both have an abstract method that given a page marker returns the next page of the result set, but concrete implementations must be created in order to properly advance each paginated collection. These abstract classes just provide the common logic.

The `FromCaller` class is just a helper to, instead of propagating the arguments of the invoked method, propagate the arguments of the caller of that method, but essentially does the same than the containing class. You can have a look at the [ParseImages](https://github.com/jclouds/jclouds-labs-openstack/blob/master/openstack-glance/src/main/java/org/jclouds/openstack/glance/v1_0/functions/internal/ParseImages.java#L65-L91) class in openstack-quantum to see an example where this is used (the arg0 version).