os.closerange(fd_low, fd_high)

for fd in xrange(fd_low, fd_high):
   try:
      os.close(fd)
   except OSError:
      pass

import os, sys

# Open a file
fd = os.open( "foo.txt", os.O_RDWR|os.O_CREAT )

# Write one string
line="this is test" 
# string needs to be converted byte object
b=str.encode(line)
os.write(fd, b)
# Close a single opened file
os.closerange( fd, fd)

print ("Closed all the files successfully!!")

Closed all the files successfully!