SerialisableObject. It can be used as a placeholder where such an object of this class, or one of its subclasses, is required. It serialises to the empty list.nilObject()
is.nilObject(object)nilObject returns the nil object. is.nilObject returns TRUE if its argument is identical to the nil object, or if it is equivalent in the sense of serialising to an identical result.J.D. Clayden, S. Muñoz Maniega, A.J. Storkey, M.D. King, M.E. Bastin & C.A. Clark (2011). TractoR: Magnetic resonance imaging and tractography with R. Journal of Statistical Software 44(8):1-18.
SerialisableObject