I’m not Anglophone, so I’m not sure. Third paragraph from end of page 21, second line : Idiomatic Ruby tends to
lean in to Ruby’s shortcuts and specific syntax.
→ is it the verb lean in followed by to …, or should it be lean into … ?
It’s probably “lean into”. I’ll change it, and the copy editor will get the last vote when the book gets its final copyedit pass. Thanks!