peek'(n, o)
i1 : s = factor 112 4 o1 = 2 7 o1 : Expression of class Product
i2 : peek s 4 o2 = Product{2 , 7}
i3 : peek'_2 s o3 = Product{Power{2, 4}, Power{7, 1}}
The object peek' is a method function.