20190525

##############encoding format#######################

plain text stored at the disk by encoding which some specifical encode format,such as utf8,gbk

py2:

str=bytes

str:bytes(stored the same format that bytes serials)(\xe8\xf0\x2a)

unicode:unicode(\u8881\u5d68)

 py3:

bytes,str

file (encode:utf8>>>)disk(read>>>)memory(interpraput>>>)#coding:[defaultcodeformat](py3 is utf8)