Write the function pascalsTriangleValue(row, col) that takes the values row and col, and returns the value in the given row and column of Pascal's Triangle where the triangle starts at row 0, and each row starts at column 0. If either row or col are not legal values (such as negative integers, floats, strings, etc.), return None, instead of crashing. Hint: math.factorial may be helpful! Also: it may help to read MathIsFun's Pascal's Triangle page, which includes a general discussion, some nice applications, and a helpful formula further down the page.