text: // File name: ExtremeC_examples_chapter22_1.c
  // Description: Definisitons of the declared functions
  
  #include "ExtremeC_examples_chapter22_1.h"
  
  int64_t next_even_number() {
    static int feed = -2;
    feed += 2;
    if (feed >= 10) {
      feed = 0;
    }
    return feed;
  }
  
  int64_t calc_factorial(int64_feed_t feed) {
    int64_t fact = 1;
    int64_t number = feed();
    for (int64_t i = 1; i <= number; i++) {
      fact *= i;
    }
    return fact;
  }
  