Pythonのmap(), reduce()

import operator
a = [1,  2,  3]
b = [10, 20, 30]
print map(operator.add, a, b)    # [11, 22, 33]  <- [1+10, 2+20, 3+30]
print map(lambda x: x*x, a)      # [1, 4, 9]     <- [1*1, 2*2, 3*3]
print reduce(lambda x,y: x+y, a) # 6             <- 1 + 2 + 3