Given a passage with a question and an answer to that question, classify if the answer actually answers the question into 'yes' or 'no'. Output 'yes' if the answer answers the question and output 'no' if the answer does not answer the question.

Ex Input:
Question: Does interaction of programmed death-1 and programmed death-1 ligand-1 contribute to testicular immune privilege?
Answer: The constitutive expression of PD-L1 in the testis is an important mechanism underlying testicular immune privilege and long-term survival of intratesticular islet allografts.

Ex Output:
yes

Ex Input:
Question: Does human Amnion-Derived Mesenchymal Stem Cell Transplantation ameliorate Liver Fibrosis in Rats?
Answer: Transplantation of hAMSCs provided significant improvement in a rat model of liver fibrosis, possibly through the inhibition of Kupffer cell and hepatic stellate cell activation. hAMSCs may be a potential new treatment for liver fibrosis.

Ex Output:
yes

Ex Input:
Question: Does urgent laparoscopic cholecystectomy in the management of acute cholecystitis : timing influence conversion rate?
Answer: The conversion rate for urgent laparoscopic cholecystectomy among patients with acute cholecystitis can be as low as 3.6%. The timing of urgent laparoscopic cholecystectomy has no impact on the conversion rate.

Ex Output:
no