def tet(a, n):
return a ** (tet(a, n - 1)) if n else 1
def main():
a = str(90)
b = str(678)
c = str(670)
loc = locals()
print(''.join(loc[ch] for ch in "abc"))
main()
my_string = "a"
mapping = [('a', 'ab'), ('b', 'bc'), ('c', 'cd'), ('d', 'de'), ('e', 'ef')]
for k, v in mapping:
my_string = my_string.replace(k, v)
print(my_string)