Deputy Prime Minister L.K. Advani today favoured a common code of conduct among chief ministers to prevent a situation like the one in Uttar Pradesh, where the Opposition accused Mayawati of unleashing political vendetta against her rivals.Advani said he would suggest to the Prime Minister to call a meeting of all chief ministers on this issue. Speaking in the Rajya Sabha, he said the CMs could evolve a common code of conduct to ensure nobody ‘‘acted in a vindictive manner in the government’’.