4. (30 pts) Explain line by line what this code does b [13, 171 print c b[0]-1 d[e+1 for e in al print d d.append (b]1) d.append (b[-1] 1) print dl-2:] for e1 in a: for e2 in b: print e1e2 4. (30 pts) Explain line by line what this code does b [13, 171 print c b[0]-1 d[e+1 for e in al print d d.append (b]1) d.append (b[-1] 1) print dl-2:] for e1 in a: for e2 in b: print e1e2