About recursive function that returns the value of learning

# About the function returns the value of the question key points; who calls back to whom: by recursive function query folder size of the problem of all files to analyze: 
# OS module: View a folder all the files in this folder there are folders, not with Walk 
# - Coding: UTF-8 - 
Import os 
Import SYS 
#C: \ the Users \ Administrator \ Desktop \ Excel 
the PATH = r'C: \ the Users \ Administrator \ Desktop \ Excel ' 
# write this function essential knowledge : 
# Print (os.getcwd ()) # get the current path 
# print (os.sep) # get the system path separator 
# returns the specified directory of all the files and folders (directories): os.listdir (the pATH) 
# test to out of the path is based on the file: os.path.isfile (the pATH) 
# verify that the absolute path: os.path.isabs () 
path # test given if there is: os.path.exists () 
# returns a path directory name and file name: os.path.split () 
# separate extension: os.path.splitext () 
# get the path name: os.path.dirname () 
# get the file name: os.path.basename () 
# get file size: os.path.getsize (filename) 

#os modules: calculating a folder for all files Size, this folder also folders, not Walk
# - * - Coding: UTF8 - * - 
Import os 
DEF lookfile (the PATH): 
    SUM = 0 
    File = os.listdir (the PATH) # get the folders and files under the path 


    for i in File: 

      RET = os.path.join ( the PATH, I) 
      IF os.path.isdir (RET): 

          RET1 = lookfile (RET) 
          SUM = + RET1 
      the else: 
         fsize = os.path.getsize (RET) 
         fsize = fsize / a float (1024 * 1024) 
         SUM = + fsize 


    return SUM 


= lookfile RET (the PATH) 
Print (RET) 
Import time 
# extended learning 
# 1, '' 'into the timestamp time: 2016-11-16 10:53:12 to 1,479,264,792' '' 
# DEF TimeStampToTime (timestamp): 
# timeStruct = time.localtime (timestamp)
The time.strftime return # ( '% Y-M-% D%% H:% M:% S', timeStruct) 
# 
# 2, '' 'get file size, the result of two decimal places, the unit is MB' ' ' 
# DEF get_FileSize (filePath): 
# = ilePath Unicode (filePath,' UTF8 ') 
# 
# = fsize os.path.getsize (filePath) 
# = fsize fsize / a float (1024 * 1024) 
# round return (fsize, 2) 
# 
# 3, '' 'to obtain file access time' '' 
# DEF get_FileAccessTime (filePath): 
# = filePath Unicode (filePath 'UTF8') 
# 
# T = os.path.getatime (filePath) 
# TimeStampToTime return (T ) 
# 
'get file creation time of the' # 4, '' ''
# 　　　 def get_FileCreateTime(filePath):
Unicode filePath = # (filePath, 'UTF8') 
# 
# T = os.path.getctime (filePath) 
# TimeStampToTime return (T) 
# 
'Get file modification time' #. 5, '' '' 
# DEF get_FileModifyTime (filePath) : 
# = filePath Unicode (filePath, 'UTF8') 
# 
# T = os.path.getmtime (filePath) 
# TimeStampToTime return (T)