pipe bunyan logger into mongodb (even with node-restify)

bunyan-pipe-to-mongodb.js

var mongoCol = require( "mongo-col" ),
    mongoStream = require( "mongo-stream" ),
    mongoInsertStream = mongoStream( mongoCol( "piped-collection", null, {
        dbOptions:{
             safe: true
        }
    })),
    Logger = require( "bunyan" );

new Logger({
    name: "pipe-into-mongodb",
    streams: [{
        type: "raw",
        stream: mongoInsertStream.insert({
             safe: true
        })
    }]
});

node-restify-audit-pipe-to-mongodb.js

var mongoCol = require( "mongo-col" ),
    mongoStream = require( "mongo-stream" ),
    restify = require( "restify" ),
    mongoInsertStream = mongoStream( mongoCol( "piped-collection", null, {
        dbOptions:{
             safe: true
        }
    })),
    Logger = require( "bunyan" ),
    server = restify.createServer();

var logger = new Logger({
    name: "pipe-into-mongodb",
    streams: [{
        type: "raw",
        stream: mongoInsertStream.insert({
            safe: true
        })
    }]
});

server.on( "after", restify.auditLogger({
    log: logger
}));

Would somebody be able/willing to provide a bit more context on how this works?