A helper function that is intended for internal use. A list ellipsis may be manipulated by overwriting (via set) or adding (via set.if.null) list elements.
defaults(ellipsis, set = NULL, set.if.null = NULL)A list, usually a list that comes from an ellipsis
A named list of parameters that are intended to be set.
A named list of parameters that are intended to be set if and only if the parameter is not already in ellipsis.