sourceAddress{string}groupAddress{string}multicastInterface{string}
Instructs the kernel to leave a source-specific multicast channel at the given
sourceAddress and groupAddress using the IP_DROP_SOURCE_MEMBERSHIP
socket option. This method is automatically called by the kernel when the
socket is closed or the process terminates, so most apps will never have
reason to call this.
If multicastInterface is not specified, the operating system will attempt to
drop membership on all valid interfaces.
