def test_power():
a, b, c, e = (Word(c) for c in 'abce')
F = FreeGroup({a, b, c, e}, e)
for x in (a, b, c, e):
assert F.power(x, 0) == e
assert F.power(x, 1) == x
assert freely_reduced(F, x + F.power(x, -1)) == e
assert F.power(x, 2) == x + x
assert F.power(x, 3) == x + x + x
