Convert an IP address from text representation into binary form.

def inet_pton(af, addr):
    """Convert an IP address from text representation into binary form."""
    # Will replace Net/Net6 objects
    addr = plain_str(addr)
    # Use inet_pton if available
    try:
        return socket.inet_pton(af, addr)
    except AttributeError:
        try:
            return _INET_PTON[af](addr)
        except KeyError:
            raise socket.error("Address family not supported by protocol")