Burrow Wheeler Transform in Python - a simple implementations

bwtransform.py

def rot(x):
	k = x[0:len(x)-1]
	k = x[len(x)-1]+(k)
	return k

x = "UnitedStatesOfAmerica"
k = x

rotations = []
rotations.append(k)
for i in range(len(x)):
	if i is 0:
		continue
	else:		
		k = rot(k)
	rotations.append(k)
#Sorting rotations
rotations = sorted(rotations)

bwtransform = ''

#Creating BW Transform
for i in range(len(rotations)):
	bwtransform+=rotations[i][len(x)-1]

#Printing BW Transform 
print 'Burrow Wheeler Transform of '+k+'\n\t'

print bwtransform