Write a function named create$\_$mat that takes two arguments, which are the number of rows $($nrows$)$ and columns $($ncols$)$ of a rectangular matrix and outputs the special matrix $($S$)$ as shown in the example below. You MUST use numpy arrays to create this matrix.

The code has already been provided to define a function named create$\_$mat that accepts the input variables nrow and ncols, and returns the output variable S$.$