code: private Node createRequireExpansionPlaceHolderNode(int index) {
  		String varName = JavaScriptModuleBuilder.EXPDEPS_VARNAME + getPadding(index);
  		Node nameNode = Node.newString(Token.NAME, varName);
  		nameNode.putProp(Node.ORIGINALNAME_PROP, varName);
  		return new Node(Token.GETELEM, new Node(Token.GETELEM, nameNode, Node.newNumber(0)), Node.newNumber(index));
  	}
docs: Creates a var reference node for the require expansion place holder variable with the given
  index. The node will correspond to javascript source similar to
  <code>_&&JAGGR_DEPS___[0][3]</code>, where 3 is the specified index.
  <p>
  The underscores preceding the first array index are of variable length for the purpose of
  keeping the source code representation of the reference constant length. For example, if
  index is 125, then the reference will be <code>_&&JAGGR_DEPS_[0][125]</code>. Index values
  greater than 999 will throw error.
  <p>
  This is done so that when the module relative index is replace with a layer relative index by
  the layer builder, the length of the source code index value can change without changing the
  code size of the reference. This is necessary to avoid invalidating source maps
  
  @param index
  the index value
  @throws IllegalArgumentException
  if index >= 999
  @return a node for the place holder reference.