'Replaces all question mark (\'?\') occurrences with a random letter
from postal_code_formats then passes result to
numerify to insert numbers'

@classmethod
def postalcode(cls):

    temp = re.sub(u'\\?', (lambda x: cls.postal_code_letter()), cls.random_element(cls.postal_code_formats))
    return cls.numerify(temp)
