static betweenPositions(position1, position2) {
        if (position1.lineNumber === position2.lineNumber) {
            return new TextLength(0, position2.column - position1.column);
        }
        else {
            return new TextLength(position2.lineNumber - position1.lineNumber, position2.column - 1);
        }
    }
Represents a non-negative length of text in terms of line and column count.