syntax_data: {"ast_node_type":"other","tokens":[{"end":38,"kind":"keyword","start":0,"text":"r21r20:"}]}
source_snippet:         r21r20: reg_pair = ["r21r20"],
context_before:         r19r18: reg_pair = ["r19r18"],
context_after:         r23r22: reg_pair = ["r23r22"],