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'))
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