def ein(self) -> str:
        """Generate a random United States Employer Identification Number (EIN).

        An United States An Employer Identification Number (EIN) is
        also known as a Federal Tax Identification Number, and is
        used to identify a business entity. EINs follow a format of a
        two-digit prefix followed by a hyphen and a seven-digit sequence:
        ##-######

        https://www.irs.gov/businesses/small-businesses-self-employed/employer-id-numbers
        """

        # Only certain EIN Prefix values are assigned:
        #
        # https://www.irs.gov/businesses/small-businesses-self-employed/how-eins-are-assigned-and-valid-ein-prefixes

        ein_prefix_choices: List[str] = [
            "01",
            "02",
            "03",
            "04",
            "05",
            "06",
            "10",
            "11",
            "12",
            "13",
            "14",
            "15",
            "16",
            "20",
            "21",
            "22",
            "23",
            "24",
            "25",
            "26",
            "27",
            "30",
            "31",
            "32",
            "33",
            "34",
            "35",
            "36",
            "37",
            "38",
            "39",
            "40",
            "41",
            "42",
            "43",
            "44",
            "45",
            "46",
            "47",
            "48",
            "50",
            "51",
            "52",
            "53",
            "54",
            "55",
            "56",
            "57",
            "58",
            "59",
            "60",
            "61",
            "62",
            "63",
            "64",
            "65",
            "66",
            "67",
            "68",
            "71",
            "72",
            "73",
            "74",
            "75",
            "76",
            "77",
            "80",
            "81",
            "82",
            "83",
            "84",
            "85",
            "86",
            "87",
            "88",
            "90",
            "91",
            "92",
            "93",
            "94",
            "95",
            "98",
            "99",
        ]

        ein_prefix: str = self.random_element(ein_prefix_choices)
        sequence = self.random_int(min=0, max=9999999)

        ein = f"{ein_prefix:s}-{sequence:07d}"
        return ein
Generate a random United States Employer Identification Number (EIN).

        An United States An Employer Identification Number (EIN) is
        also known as a Federal Tax Identification Number, and is
        used to identify a business entity. EINs follow a format of a
        two-digit prefix followed by a hyphen and a seven-digit sequence:
        ##-######

        https://www.irs.gov/businesses/small-businesses-self-employed/employer-id-numbers
        
faker/providers/ssn/en_US/__init__.py