python 驻留机制

>>> s1 = '111'
>>> s2 = '111'
>>> s3 = "111"
>>> id(s1)
2385244511728
>>> id(s2) 
2385244511728
>>> id(s3) 
2385244511728
>>> s4 = '''111''' 
>>> id(s4)
2385244511728

但是

>>> s5 = 'ac@'
>>> s6 = 'ac@'
>>> id(s5)
2385244511920
>>> id(s6) 
2385244512176

即 不符合标识符规则的串 不满足驻留机制