text: #ifndef SRC_CHANNEL_H
  #define SRC_CHANNEL_H
  
  #include <stdio.h>
  #include <unistd.h>
  #include <string.h>
  #include <sys/wait.h>
  #include <unistd.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <sys/wait.h>
  
  #define NUM_FD (2)
  
  #include <stdlib.h>
  
  struct sender{
  
    int write; // write end
    size_t msg_sz;
  };
  
  struct receiver{
  
    int read; // read end
    size_t msg_sz;
  };
  
  void channel_init(struct receiver* recv, struct sender* sender,
    size_t msg_sz);
  
  void channel_get(struct receiver* channel, void* data);
  
  void channel_send(struct sender* channel, void* data);
  
  void sender_dup(struct sender* dest, struct sender* src);
  
  void channel_destroy(struct receiver* recv, struct sender* sender);
  
  #endif
  