What is the modulus operator in Nim?
tile % 9 == 0 results in undeclared identifier: '%'
Googling or searching SO doesn't bring up an answer.
Others have suggested using %%, but don't do that. It is a remnant of a time when Nim used to have only signed integers. The operators ending with % like <% are used to handle these signed integers as unsigned ints. Since Nim has had unsigned integers for a while now, simply use the mod operator that is correctly overloaded for all relevant integral types: https://nim-lang.org/docs/system.html#mod,int,int