import dis

def single():
    'Hello' + ', ' + 'World'

def double():
    "Hello" + ", " + "World"

print('Single quotes')
dis.dis(single)

print('Double quotes')
dis.dis(double)



Python 3.4.1

Single quotes
  6           0 LOAD_CONST               5 ('Hello, World')
              3 POP_TOP
              4 LOAD_CONST               0 (None)
              7 RETURN_VALUE
Double quotes
  9           0 LOAD_CONST               5 ('Hello, World')
              3 POP_TOP
              4 LOAD_CONST               0 (None)
              7 RETURN_VALUE

Python 2.7.8
Single quotes
  6           0 LOAD_CONST               5 ('Hello, World')
              3 POP_TOP
              4 LOAD_CONST               0 (None)
              7 RETURN_VALUE
Double quotes
  9           0 LOAD_CONST               5 ('Hello, World')
              3 POP_TOP
              4 LOAD_CONST               0 (None)
              7 RETURN_VALUE