text: #include <stdio.h>
  #include "two_fer.h"
  
  #define BUFFER_SIZE (100)
  #define SEQUENCE "One for %s, one for me."
  
  void two_fer(char *buffer, const char *name)
  {
    snprintf(buffer, BUFFER_SIZE, SEQUENCE,
        (buffer == NULL || name == NULL) ? "you" : name);
  }
  