Design an editable sequence with marker

Create a mutable ordered collection of elements that also maintains a marker referencing at most one element. The collection must support four kinds of edits: inserting a consecutive block at a chosen position, deleting a consecutive block, relocating a consecutive block from one position to another, and moving the marker to a new location. Define the public API and the underlying data model. Clearly specify the marker's behavior in each of these cases: an edit occurs…