[
    Interface {
        name: Identifier {
            name: "A",
        },
        extends: [],
        body: [],
    },
    Interface {
        name: Identifier {
            name: "B",
        },
        extends: [],
        body: [],
    },
    Interface {
        name: Identifier {
            name: "C",
        },
        extends: [],
        body: [],
    },
    Interface {
        name: Identifier {
            name: "D",
        },
        extends: [],
        body: [],
    },
    Function {
        name: Identifier {
            name: "foo",
        },
        params: [
            Param {
                name: Variable {
                    name: "a",
                },
                type: Some(
                    Union(
                        [
                            Identifier(
                                Identifier {
                                    name: "A",
                                },
                            ),
                            Intersection(
                                [
                                    Identifier(
                                        Identifier {
                                            name: "B",
                                        },
                                    ),
                                    Identifier(
                                        Identifier {
                                            name: "C",
                                        },
                                    ),
                                    Identifier(
                                        Identifier {
                                            name: "D",
                                        },
                                    ),
                                ],
                            ),
                        ],
                    ),
                ),
                variadic: false,
                default: None,
                flags: [],
                by_ref: false,
            },
        ],
        body: [
            Expression {
                expr: Call {
                    target: Identifier {
                        name: "exit",
                    },
                    args: [
                        Arg {
                            name: None,
                            value: LiteralInteger {
                                i: 0,
                            },
                            unpack: false,
                        },
                    ],
                },
            },
        ],
        return_type: Some(
            Intersection(
                [
                    Identifier(
                        Identifier {
                            name: "A",
                        },
                    ),
                    Union(
                        [
                            Identifier(
                                Identifier {
                                    name: "B",
                                },
                            ),
                            Identifier(
                                Identifier {
                                    name: "C",
                                },
                            ),
                            Identifier(
                                Identifier {
                                    name: "D",
                                },
                            ),
                        ],
                    ),
                ],
            ),
        ),
        by_ref: false,
    },
]