Suggestion to change line of code

[JuanPabloGil]

I think you can improve this line if you change it for a default variable equal to false because you check if the position it's equal to a string, and the inputs always will be equal to string.

https://github.com/Israel-Laguan/Tic-Tac-Toe/blob/b1aa4f65611fdb8710f4377ce454b10499dc7c20/lib/tic_tac_toe.rb#L46