code: function buffer_empty(buf) {
    for (var i = buf.length - 1; i > 0; i--) {
      if (buf[i]) { return false; }
    }
  
    return true;
  }
docs: internal
  buffer_empty(buf) -> Boolean
  - buf(Buffer): buffer to check
  
  Returns true iff all elements of a buffer are zero.