ViewsList is a virtual class.
  Specialized subclasses like e.g. RleViewsList are useful
  for storing coverage vectors over a set of spaces (e.g. chromosomes),
  each of which requires a separate RleViews object.  As a Vector subclass, ViewsList may be annotated with its
  universe identifier (e.g. a genome) in which all of its spaces exist.
  As a List subclass, ViewsList inherits all the methods
  available for List objects. It also presents an API that
  is very similar to that of Views, where operations are
  vectorized over the elements and generally return lists.