346. Signature essential to liability
No person is liable as drawer, indorser, or acceptor of a bill who has not signed it as such: Provided that —
(1) where a person signs a bill in a trade or assumed name, he or she is liable thereon as if he or she had signed it in his or her own name;
(2) the signature of the name of a firm is equivalent to the signature by the person so signing of the names of all persons liable as partners in that firm.