HomeSYNOPSIS
flag = httpd:listen([port])
DESCRIPTION
If port is non-nil, starts processing client requests on the specified port.
By calling this function with a nil value, the server stops accepting new client request. This is useful if the web server needs to be enabled or disabled dynamically.
When the server is enabled, calling httpd:listen() again with a different port number will fail. Disable the server first, then re-enable with the new port number.
If you want to support encrypted SSL/TLS connections, use httpd:secureListen() instead.
RETURN VALUE
On success, returns true. On error, three values are returned: nil, a
string describing the error (The result of the C library call strerror() on the errno code) and the errno
number from the standard C library.