According to [SRFI 1](https://srfi.schemers.org/srfi-1/srfi-1.html#FoldUnfoldMap), `fold` and `fold-right` can accept variable number of lists (instead of just 1). Relevant code is [here](https://github.com/LiiiLabs/goldfish/blob/43bb07199777f786456e997983958102960e6be7/goldfish/srfi/srfi-1.scm#L144).
