Pos is a position in between two elements in a list. For example, position
0 marks the beginning of the list, and position
length list marks the end of the list. There are
n + 1 valid positions for a list of length
Yields the element's range.
Yields the element's begin position.
Yields the element's end position.
distRange (b1, e1) (b2, e2) is defined as
|b1 - b2| + |e1 - e2|.
Whether a position falls within a range, including the range's edges.
Yields whether the second argument completely falls within the first argument.