lib/containers.js
function copyBuffer(buf, pos, len) {
  var copy = new Buffer(len);
  buf.copy(copy, 0, pos, pos + len);
  return copy;
}
function copyBuffer(buf, pos, len) {
  var copy = new Buffer(len);
  buf.copy(copy, 0, pos, pos + len);
  return copy;
}
function copyBuffer ( buf , pos , len ) { var copy = new Buffer ( len ) ; buf . copy ( copy , 0 , pos , pos + len ) ; return copy ; }
Copy a buffer.

This avoids having to create a slice of the original buffer.
Copy a buffer .