fallback_region: String,
Мир Российская Премьер-лига|20-й тур
，这一点在新收录的资料中也有详细论述
“Ticketmaster gives her money back when the sales happen on the secondary platform, so all of the additional surplus goes to her,” he explained. “She ends up with the same high price, but there’s other people in the process [in] between.”
ITE stands for if-then-else. ITE([a-z], leaf(R1), leaf(R2)) means: “if the character is in [a-z], the derivative is R1, otherwise it’s R2”. these trees can nest, splitting the character space into finer partitions as needed. the key insight is that the derivative function never takes a character argument - it produces a complete map from all possible characters to their resulting states in one shot.