Function plugin_loop_io 

pub fn plugin_loop_io<R, W, F>(reader: R, writer: W, handler: F) -> Result<()>
where
    R: BufRead,
    W: Write,
    F: FnMut(PluginRequest) -> PluginResponse,

runs a newline-delimited json plugin loop over the given reader and writer.

the handler is invoked once per request. responses are serialized back to the writer. use plugin_loop for the common case of stdin/stdout.