python的tab模块

#python startup file 
import sys
import readline
import rlcompleter
#import atexit
import os
#tab completion
readline.parse_and_bind('tab: complete')
#history file
histfile = os.path.join(os.environ['HOME'],'.pythonhistory')
#try:
#        readline.read_history_file(histfile)
#except IOError:
#        pass
#atexit.register(readline.write_history_file,histfile)