def remove_all(a, b):
	f = b.find(a)
	return remove_all(a, b[:f] + b[f+len(a):]) if f > -1 else b

print(remove_all('an', 'banana'))
print(remove_all('cyc', 'bicycle'))
print(remove_all('iss', 'Mississippi'))
print(remove_all('eggs', 'bicycle'))