Python 3: detect encoding

detect_encoding.py

#detect files' encoding
#tested under Python3
from chardet.universaldetector import UniversalDetector
import os
import os.path

def detect(filename, filetype, out_enc='utf-8'):
    (filepath, name) = os.path.split(filename)
    if filetype == os.path.splitext(name)[1]:
        try:
            f = open(filename, 'rb')
            b = b' '
            b += f.read(1024)
            u = UniversalDetector()
            u.reset()
            u.feed(b)
            u.close()
            f.seek(0)
            b = f.read()
            f.close()
            in_enc = u.result['encoding']
            print(filename + ' is ' + in_enc)
        except IOError:
            print('Error:' + filename + ' fail to converted from ' + in_enc + ' to ' + out_enc)
        finally:
            f.close()
    else:
        return

def find_and_operate(sou_dir, filetype, isloop_subdir = True):
    if '' == filetype:
        print('filetype is not defined')
        print('Quit')
        return
    else:
        for item in os.listdir(sou_dir):
            subdir = os.path.join(sou_dir, item)
            if os.path.isfile(subdir):
                detect(subdir, filetype,'utf-8')
            else:
                if isloop_subdir:
                    find_and_operate(subdir, filetype, isloop_subdir)
                else:
                    pass

def main():
    directory = input('directory:')
    flag = input('is loop sub dir(t or f, Default is True):')
    if (flag == '') | (flag == 't'):
        isloop_subdir = True
    else:
        isloop_subdir = False

    filetype = input('file suffix(must defined):')
    find_and_operate(directory, filetype, isloop_subdir)

if __name__ == '__main__':
    main()