format-network-address
format-network-address is a built-in function in `C source code
'.
(format-network-address ADDRESS &optional OMIT-PORT)
Convert network ADDRESS from internal format to a string.
A 4 or 5 element vector represents an IPv4 address (with port number).
An 8 or 9 element vector represents an IPv6 address (with port number).
If optional second argument OMIT-PORT is non-nil, don't include a port
number in the string, even when present in ADDRESS.
Returns nil if format of ADDRESS is invalid.