treemap.paddingRight()

treemap.paddingRight([padding])

If padding is specified, sets the right padding to the specified number or function and returns this treemap layout. If padding is not specified, returns the current right padding function, which defaults to the constant zero. If padding is a function, it is invoked for each node with children, being passed the current node. The right padding is used to separate the right edge of a node from its children.