Do you think why Dumbledore was saying "Severus, please..." is just because he was asking Snape to kill him??

In The Half Blood Prince, I personally think that Dumbledore was asking Snape to kill him so they could fool the Death Eaters and Voldemort as well, in convincing that Snape's at the Dark Lord's side?? Do you think it's a plan of Dumbledore and Snape? I mean, Albus Dumbledore trusted Snape very well, and I don't believe that Dumbledore would just simply believe anybody if he/she isn't trustworthy. But again, Snape is an acomplished Occlumens. Dumbledore wouldn't know if he's really reformed, he wouldn't know what he's thinking, would he? Anyway, I just wanna know opinions on this matter.