XXX = range(4)

print [i for i in XXX]
print
print [i for i in (1, 2, 3, 4)]
print
print [(i, 1) for i in XXX]
print
print [i * 2 for i in range(4)]
print
print [i * j for i in range(4) for j in range(7)]
print [i * 2 for i in range(4) if i == 0]
print [(i, i ** 2) for i in range(4) if i % 2 == 0]
print [i * j for i in range(4) if i == 2 for j in range(7) if i + (i % 2) == 0]

seq1 = 'abc'
seq2 = (1, 2, 3)
[(x, y) for x in seq1 for y in seq2]

def flatten(seq):
    return [x for subseq in seq for x in subseq]

print flatten([[0], [1, 2, 3], [4, 5], [6, 7, 8, 9], []])