WHAT IS A HIERARCHICAL METHOD?
An object’s methods are subcommands of the object’s instance command. Hierarchical methods allow an object’s methods to have subcommands of their own; and these can in turn have subcommands, and so on. This allows the programmer to define a tree-shaped command structure, such as is used by many of the Tk widgets–the subcommands of the Tk text widget’s tag method are hierarchical methods.