Fixed the absence of the nodes attribute in simplified node copying.
Fixed the builtins, removing artifacts of list-based tuples and other historical
mechanisms.
1classA: 2"A class with attribute and method." 3x=123.456 4x2=x 5 6defm(self,x): 7self.x=x 8 9defn(self,y=A.x): 10self.y=y 11n2=n 12 13a1=A() 14a2=A() 15y=A.x 16a1.m(321) 17a2.m("321") 18z1=a1.x 19z2=a2.x 20a1.n(123) 21a2.n("123") 22a2.n()