Question: What revolutionary movement that sought to define a Mexican identity did this Mexican painter whose work includes "Self-Portrait with Thorn Necklace and Hummingbird" participate in?
Sentence (from "Self-Portrait with Thorn Necklace and Hummingbird"): Self-Portrait with Thorn Necklace and Hummingbird ("Autorretrato con Collar de Espinas") is a 1940 painting by Mexican painter Frida Kahlo.
Relevant evidence: Yes