Remove multiple spaces from a file

single_space.py

def single_space(fileName):
    """
    remove multiple spaces from a file
    """
    input = open(fileName, 'r')
    output = open('tmp.txt', 'w')
    output.write(string.join(input.read().split()))
    input.close()
    output.close()
    os.remove(fileName)
    os.rename('tmp.txt', fileName)