pascals_triangle(n) that returns the first n rows of Pascal's Triangle as a list of lists, where each row is computed iteratively from the previous row (do not use math.comb).pascals_triangle(4)
[[1], [1, 1], [1, 2, 1], [1, 3, 3, 1]]
Each interior value is the sum of the two values above it in the previous row.
Start with row [1], then for each new row, build it from the previous row: edges are always 1, interior values sum adjacent pairs from the previous row.
A nested loop over row index and column index works well.