def METHOD_NAME(
    self, address: str, access_class: str = "allow"
) -> None:
    """Adds an address to an address list (either allow or deny)."""
    address = address.lower()
    if not self.credentials or access_class not in self.credentials:
        self.credentials[access_class] = [{"type": "address", "values": [address]}]
        return
    address_entry = self.get_address_entry_of_class(access_class)
    if not address_entry:
        self.credentials[access_class].append(
            {"type": "address", "values": [address]}
        )
        return
    lc_addresses = self.get_addresses_of_class(access_class)
    if address not in lc_addresses:
        lc_addresses.append(address)
    address_entry["values"] = lc_addresses