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I got this chunk of code I can't really comprehend. I got stuck after it replaced pow2s's g to a map's gen structure. And from there, I can't see how it continues tracking the value, and how it is stored. The code compiles and runs. Can someone help me understand this code? Thanks! PS: I'm learning C It is translated from the follow Python code: >>> def pow2s(): yield 1 for i in map((lambda x:2*x),pow2s()): yield i >>> def mymap(f,iter): for i in iter: yield f(i) And the translated C code: #include <stdio.h> #include <stdlib.h> struct gen { // generic structure, the base of all generators int (*next)() ; int continue_from ; } ; typedef int (*fptr)() ; // Each iterator has 3 components: a structure, a constructor for the structure, // and a next function // map struct mapgen { // structure for map int (*next)() ; int continue_from ; // not really required, provided for compatibility fptr f ; struct gen *g ; } ; int map_next(struct mapgen *p) { // next function for map return p->f(p->g->next(p->g)) ; } struct gen *map(fptr f, struct gen *g) { // constructor for map iterator struct mapgen *p = (struct mapgen *)malloc(sizeof(struct mapgen)); p->next = map_next; p->continue_from = 0; p->f = f; p->g = g; return (struct gen *)p ; } // powers of 2 struct pow2s { // structure int (*next)() ; int continue_from ; struct gen *g ; }; int times2(int x) { // anonymous lambda is translated into this return 2*x ; } struct gen *pow2() ; // forward declaration of constructor int pow2next(struct pow2s * p){ // next function for iterator switch(p->continue_from) { case 0: p->continue_from = 1; return 1; case 1: p->g = map(times2,pow2()) ; p->continue_from = 2; return p->g->next(p->g) ; case 2: p->continue_f

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