9-405. Proof of writings. Any writing may be proved either:
1. By any one who saw the writing executed; or
2. By evidence of the genuineness of the handwriting of the maker; or
3. By a subscribing witness.
[(9-405) C.C.P. 1881, sec. 926; R.S., R.C., & C.L., sec. 5993; C.S., sec. 7964; I.C.A., sec. 16-405.]