What this snippet does
TypeScript arrays are covariant, meaning an array of subtypes can be assigned to an array of base types.
Expected output
1
Why practise typing this
Typing advanced generics code builds muscle memory for the symbols and indentation TypeScript uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.
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