Reduce and Parallel Prefix - DummyArray type definition not working

I am trying to learn Julia and I come across this set of great tutorials.

However, when something in the tutorial went wrong, I am not yet equipped to fix it.

for the prefix notebook, the definition of DummyArray gave out an error syntax: extra token "DummyArray" after end of expression

the definition is as below:

isdefined(:DummyArray) || type DummyArray
    length :: Int
    read :: Vector
    history :: Vector{Any}
    DummyArray(length, read=[], history=[])=new(length, read, history)
end

I tried JuliaBox to run the same code, and it yielded the same error message. I am a bit lost as to what the example is trying to demonstrate and how exactly should I define a type in Julia? is it with type or struct keyword? I tried struct and no luck.

Search the prefix notebook for the DummyArray definition shown in the issue and run that cell with the repository's tutorial environment. Check the Julia type syntax against the version used by the tutorial, then verify that the notebook proceeds past the definition without the reported syntax error.