ReferenceError: socket is not defined
   at /home/ubuntu/nodejs_server/server.js:93:32
   at Layer.handle [as handle_request] (/home/ubuntu/nodejs_server/node_modules/express/lib/router/layer.js:95:5)
   at trim_prefix (/home/ubuntu/nodejs_server/node_modules/express/lib/router/index.js:323:13)
   at /home/ubuntu/nodejs_server/node_modules/express/lib/router/index.js:284:7
   at Function.process_params (/home/ubuntu/nodejs_server/node_modules/express/lib/router/index.js:341:12)
   at next (/home/ubuntu/nodejs_server/node_modules/express/lib/router/index.js:275:10)
   at urlencodedParser (/home/ubuntu/nodejs_server/node_modules/body-parser/lib/types/urlencoded.js:91:7)
   at Layer.handle [as handle_request] (/home/ubuntu/nodejs_server/node_modules/express/lib/router/layer.js:95:5)
   at trim_prefix (/home/ubuntu/nodejs_server/node_modules/express/lib/router/index.js:323:13)
   at /home/ubuntu/nodejs_server/node_modules/express/lib/router/index.js:284:7