#= none:1 =# @test_expr JLStruct mutable struct Mutable
            const x::Int
            y::Int
        end
    def = #= none:6 =# @expr(JLKwStruct, mutable struct MutableKw
                const x::Int = 1
                y::Int = 2
            end)
    #= none:11 =# @test_expr codegen_ast(def) == quote
                mutable struct MutableKw
                    const x::Int
                    y::Int
                end
                function MutableKw(; x = 1, y = 2)
                    MutableKw(x, y)
                end
                nothing
            end