PRINT-ATTR_ARGS INPUT (DISPLAY): a, line!(), b
PRINT-ATTR_ARGS DEEP-RE-COLLECTED (DISPLAY): a, line! (), b
PRINT-ATTR_ARGS INPUT (DEBUG): TokenStream [
    Ident {
        ident: "a",
        span: $DIR/nonterminal-expansion.rs:13:27: 13:28 (#3),
    },
    Punct {
        ch: ',',
        spacing: Alone,
        span: $DIR/nonterminal-expansion.rs:13:28: 13:29 (#3),
    },
    Group {
        delimiter: None,
        stream: TokenStream [
            Ident {
                ident: "line",
                span: $DIR/nonterminal-expansion.rs:19:19: 19:23 (#0),
            },
            Punct {
                ch: '!',
                spacing: Alone,
                span: $DIR/nonterminal-expansion.rs:19:23: 19:24 (#0),
            },
            Group {
                delimiter: Parenthesis,
                stream: TokenStream [],
                span: $DIR/nonterminal-expansion.rs:19:24: 19:26 (#0),
            },
        ],
        span: $DIR/nonterminal-expansion.rs:13:30: 13:35 (#3),
    },
    Punct {
        ch: ',',
        spacing: Alone,
        span: $DIR/nonterminal-expansion.rs:13:35: 13:36 (#3),
    },
    Ident {
        ident: "b",
        span: $DIR/nonterminal-expansion.rs:13:37: 13:38 (#3),
    },
]