Update Cascading.jl

[PyDataBlog]

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Currently matchFirst function isn't exported and since this is a key extraction function commonly expected to be used, this function should be exported for ease of access. What do you think?

[aviks]

Investigating why this function needs exporting, I realised, our usage here is slightly different from base.

I think matchfirst should just become Base.match. We do have a match function, but that behaves differently from how base sees that function. I think we should lean in to base, and make matchfirst become match.

What do you think?

[PyDataBlog]

I think leaning on base is the right choice too.