text: #include "assert.h"
  
  int main() {
    char *s = "the quick brown fox jumps over the lazy dog", *p = s;
    int i = 0;
    while (*p != 0) {
      if (*p == 'e') i += 1;
      p += 1;
    }
    assert(i == 3);
    return 0;
  }
  