TO_STR

TO_STR(123) returns 123 (as string)

TO_STR(123) + "_000" or CONCAT(TO_STR(123), "_000") returns 123_000

TO_STR("some_string") returns some_string (no effect)

TO_STR([1,2,3]) returns [1,2,3] (as string)

TO_STR([1,2,3]) + " is my array" returns [1,2,3] is my array