Mono Web Service Discovery Tool 4.2.1.0 ERROR: URL to discover not provided System.Exception: URL to discover not provided at Driver.Main (System.String[] args) <0x40c95e90 + 0x000fb> in <filename unknown>:0

Mono Web Service Discovery Tool 4.2.1.0 Usage: disco [options] url Options: -nologo Supress the startup logo -nosave Do not save the discovered documents to disk. The default is to save the documents. -o -out:directory The directory where to save the discovered documents. By default, documents are saved in the current directory. -u -username:username -p -password:password -d -domain:domain The credentials to use when connecting to the server. -proxy:url The url of the proxy server to use for http requests. -proxyusername:name -proxypassword:pwd -proxydomin:domain The credentials to use when connection to the proxy.