def foo(step=0):
for i in range(0, 4):
print step
for i in range(step+1, 4):
print step+1
for i in range(step+2, 4):
print step+2
for i in range(step+3, 4):
print step+3
for i in range(step+4, 4):
print step+4
# No more recursion
# range(step+4, 4) == range(4,4) == []
foo()
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