Tag: io	Buffered event driven IO. Set up a file descriptor, and use this to do input or output on it.
Attrib Name	Type	Possible Values	Description
_sendq	string	null	Stuff data into the outbound send queue.
fd	integer	-1,*	Specify the file descripter to watch.
mode	string	chunk,line	Specify whether to pass lines or binary chunks.
onerror	function	null	Function to call when an exception occurs on the fd.
onnewdata	function	null	Function to call with data read from the fd.
onwrite	function	null	Function to call with the number of bytes written to fd.