def resistance():
r1 = float(input('R1 = '))
r2 = float(input('R2 = '))
r3 = float(input('R3 = '))
return 1/(1/r1 + 1/r2 + 1/r3)
def resistance():
r1 = float(input('R1 = '))
r2 = float(input('R2 = '))
r3 = float(input('R3 = '))
return 1/(1/r1 + 1/r2 + 1/r3)