syntax_data: {"ast_node_type":"import","tokens":[{"end":99,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // But we are not guaranteed to be at the end of the file, because we did not attempt to do
context_before:         // At this point, we've read all the bytes that filesystem metadata reported exist.
context_after:         // a read with a non-zero-sized buffer and get Ok(0).