This appears to be inaccurate (probably out of date because that tutorial was deprecated in favor of [dustjs.com](https://www.dustjs.com/), but the latter is incomplete and lacking any reference to the `@size` helper.
Corrections
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- Booleans are 0, not converted to strings
Oddities
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Reference parameters (like `foo="{bar}"`) are usually treated as strings but it seems if it contains ONLY a reference to a value and not anything else, then it is still treated as a number.