Theindex()function in Appian is used to replace an element at a specified index in a list. In the code snippetindex({"a", "b", "c"}, 1, "x"), the function is called to replace the element at index 1 of the list{"a", "b", "c"}with the string"x". Since Appian lists are 1-indexed, this means that the first element "a" will be replaced by "x". However, since the function is used to modify a list and not to return a value, if this function is used as is without being part of a larger expression that outputs the list, it would not return any of the listed values.References:Appian Expression Language Documentation - Functions