Add a security group rule to group <sgid>.
           Direction is either 'in' (ingress) or 'out' (egress).
           See modify() for other parameters.

def add(self, sgid, other, proto_spec, direction="in"):
        """Add a security group rule to group <sgid>.
           Direction is either 'in' (ingress) or 'out' (egress).
           See modify() for other parameters."""
        # returns bool
        # AuthorizeSecurityGroupIngress, AuthorizeSecurityGroupEgress
        if direction == "in":
            api = "AuthorizeSecurityGroupIngress"
        elif direction == "out":
            api = "AuthorizeSecurityGroupEgress"
        else:
            raise ValueError("direction must be one of ('in', 'out')")
        return self.modify(api, sgid, other, proto_spec)