Out-Of-Bounds Indexing

Accessing a set element by index or a subset of elements by range, might select an element outside the bounds of the ordered set. Negative indexes, by definition, point to missing elements and so do indexes that are too large. The example below holds four such out-of-bound expressions:

    `print set[-2];          // Negative indexes are out of bounds by definition.
    `print set[0];           // An index of zero is out of bounds by definition.
    `print set[#set + 10];   // #set + 10 is out of bounds by 10.
    `print {1..9}[10];       // This expression is out of bounds by 1.
         

All four of the above `print statements will return the same value, the missing value for the element type of the set.