struct baz;                  /* just says "a struct of this name exists"   */
void swizzle(struct baz *);  /* just says "a function of this name exists" */
/*
typedef struct {
    int x;
    int y = 3;
} test;
*/
/* Swizzles an array of struct bazs                           *
 * This code does not need to understand what a struct baz is */
 void swozzle(struct baz **x, int n) {
 //   test w;
     for(int i=0; i<n; i+=1) swizzle(x[i]);
 }