-func EachCollection(c *arvados.Client, f func(arvados.Collection) error, progress func(done, total int)) error {
+//
+// If pageSize > 0 it is used as the maximum page size in each API
+// call; otherwise the maximum allowed page size is requested.
+func EachCollection(c *arvados.Client, pageSize int, f func(arvados.Collection) error, progress func(done, total int)) error {