For each of the following Python programs P and input strings I, give the output P(I), using the formal definition of P(I) given in section 2.5, and employing any reasonable reference computer C:

(a) P = def f(x): return x[-2], I = abcdefgh

(b) P = def f(x): return x+5, I = 43

(d) P = def f(x): return x[3:7], I = abcdefghij

Which pairs of the following Python programs are equivalent?

P = def f(x): return str(len(x)+1)

Q = def f(x): return str(len(x+'a'))

R = def f(x): L=1 while L!=len(x): L=L+1 return str (L+1) (note that all lines except the first are indented here)