/in/foo.cs(20,29): error CS1061: Type `int[]' does not contain a definition for `Append' and no extension method `Append' of type `int[]' could be found. Are you missing `System.Linq' using directive?
/usr/lib/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)
/in/foo.cs(30,59): error CS1061: Type `string[]' does not contain a definition for `ToArray' and no extension method `ToArray' of type `string[]' could be found. Are you missing `System.Buffers' or `System.Linq' using directive?
/usr/lib/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)
Compilation failed: 2 error(s), 0 warnings