pub fn recognize_gelu(stmts: &[Stmt<'_>]) -> Option<GeluSpec>
Recognize Let Y be gelu of X — Push X[i] / (1 + E^(0 − 2z)) with the 0.044715 cubic in z.
Let Y be gelu of X
Push X[i] / (1 + E^(0 − 2z))
z