syntax_data: {"ast_node_type":"other","tokens":[{"end":34,"kind":"keyword","start":0,"text":"x20:"}]}
source_snippet:         x20: reg = ["x20", "w20"],
context_before:         x18: reg = ["x18", "w18"] % reserved_x18,
context_after:         x21: reg = ["x21", "w21"],