python to get a list of all filenames in a given directory

# -*- coding: utf-8 -*- 
#~ #------------------------------------------------------------------
#~ module:wlab 
#~ Filename: 
#~ Function : 
#~ def IsSubString(SubStrList,Str) 
#~ def GetFileList(FindPath,FlagStr=[]): 
#~ Function:Reads a list of file names of a specific type in a specified directory.
#~ Data: 2013-08-08,Thursday
#~ Author:Wu Xu Ping
#~ Email:wxp07@ 
#~ #------------------------------------------------------------------
#~ #------------------------------------------------------------------
def IsSubString(SubStrList,Str): 
 ''''' 
 # Determine whether the string Str contains every substring in the sequence SubStrList.
 #>>>SubStrList=['F','EMS','txt'] 
 #>>>Str='' 
 #>>>IsSubString(SubStrList,Str)#return True (or False) 
 ''' 
 flag=True 
 for substr in SubStrList: 
  if not(substr in Str): 
   flag=False 
 return flag 
#~ #---------------------------------------------------------------------- 
def GetFileList(FindPath,FlagStr=[]): 
 ''''' 
 # Get the name of the specified file in the directory
 #>>>FlagStr=['F','EMS','txt'] #Require these characters in the file name
 #>>>FileList=GetFileList(FindPath,FlagStr) # 
 ''' 
 import os 
 FileList=[] 
 FileNames=(FindPath) 
 if (len(FileNames)>0): 
  for fn in FileNames: 
   if (len(FlagStr)>0): 
    # Returns a filename of the specified type
    if (IsSubString(FlagStr,fn)): 
     fullfilename=(FindPath,fn) 
     (fullfilename) 
   else: 
    #The default is to return all filenames directly
    fullfilename=(FindPath,fn) 
    (fullfilename) 
 # Sort file names
 if (len(FileList)>0): 
  () 
 return FileList

pip install wlab