A test that featured nested arrays just happens to work, but nested arrays will not be removed if they’re duplicates by the current solution of this challenge. See issue #18265
In spanish, the "ignoring case" statement is better translated as "ignorando mayúsculas y minúsculas". More information: https://www.linguee.es/ingles-espanol/traduccion/case+insensitive.html https://spanish.stackexchange.com/questions/17018/case-sensitive-en-castellano
