Hi I am translating an article about Giles Peterson and his career. I have this sentence that I cannot fathom: Que ce soit en funk, soul, afro, electro, latino ou jazz, la diffusion par Giles Peterson est un diplome et un sésame. So the writer is talking about his radio shows that Giles Broadcast's and I'm not sure what they mean by un diplome et un sésame is this some sort of saying? Does it mean that his show is an immense achievement or something? I'd appreciate any help, thanks!