Printable Pseudo Electronic Serial Number.

    :param number: hexadecimal string

    >>> print(pesn('1B69B4BA630F34E'))
    805F9EF7

def pesn(number, separator=u''):
    '''
    Printable Pseudo Electronic Serial Number.

    :param number: hexadecimal string

    >>> print(pesn('1B69B4BA630F34E'))
    805F9EF7
    '''

    number = re.sub(r'[\s-]', '', meid(number))
    serial = hashlib.sha1(unhexlify(number[:14]))
    return separator.join(['80', serial.hexdigest()[-6:].upper()])