```
from copy import deepcopy
G = []
cycles = []
point_stack = []
marked = []
marked_stack = []
def tarjan(s, v):
global cycles
f = False
point_stack.append(v)
marked[v] = True
marked_stack.append(v)
for w in G[v]:
if w < s:
G[w] = []
elif w == s:
points_keeper = list(deepcopy(point_stack))
if points_keeper not in cycles:
cycles.append(points_keeper)
f = True
elif marked[w] == False:
g = tarjan(s,w)
f = f or g
if f == True:
while marked_stack[len(marked_stack) - 1] != v:
u = marked_stack.pop()
marked[u] = False
marked_stack.pop()
marked[v] = False
point_stack.pop()
return f
def entry_tarjan(G_):
global G, cycles, marked, marked_stack, point_stack
G = []
cycles = []
point_stack = []
marked = []
marked_stack = []
G = deepcopy(G_)
marked = [False for x in xrange(0, len(G_))]
for i in range(len(G)):
tarjan(i, i)
while marked_stack:
u = marked_stack.pop()
marked[u] = False
return cycles
```