[#2298405A8B1EC36124CCC56046F902FCE009D31C]
Return true if a port is present
bool has_port() const noexcept;
This function returns true if an authority is present and contains a port.
assert( url_view( "wss://www.example.com:443" ).has_port() );
Constant.
Throws nothing.
authority = [ userinfo "@" ] host [ ":" port ]
port = *DIGIT