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The lexical structure is [here](https://ruby-doc.org/docs/ruby-doc-bundle/Manual/man-1.4/syntax.html). However, [the rules are complex](https://idiosyncratic-ruby.com/29-limitations-of-language.html), and the solutions [require taking into account considerable context](https://stackoverflow.com/questions/32159070/how-does-ruby-know-when-is-a-divide-symbol-vs-when-it-starts-a-regular-exp).