[
    Declare {
        declares: [
            DeclareItem {
                key: Identifier {
                    name: "A",
                },
                value: LiteralString {
                    value: "B",
                },
            },
        ],
        body: [
            Echo {
                values: [
                    LiteralString {
                        value: "Hello, world!",
                    },
                ],
            },
        ],
    },
]