Python nested loops

A loop inside a loop: for each turn of the outer loop, the inner one runs all the way through. Good for rows and columns.

print(..., end="") stays on the same line; an empty print() after the inner loop moves to the next row.

for row in range(1, 4):
    line = []
    for col in range(1, 4):
        line.append(str(row * col))
    print(" ".join(line))

Watch for: print(x, end=" ") leaves a space at the end of every line, and the tests see it. Build each line as a list and print " ".join(line): spaces only between.