getting the phone number provider in Tanzania. Feel free to modify

phonenumber_provider.py

_carriers = {
    'Tigo Tanzania': ['071', '065', '067'],
    'Airtel Tanzania': ['078', '068', '069'],
    'Vodacom Tanzania': ['075', '076', '074'],
    'TTCL': ['073'],
    'Halotel': ['061', '062'],
    'Zantel': ['077'],
}


def get_phone_carrier(phone: str) -> str:
    # add the 255 to the front of the string
    if phone.startswith('255') and not phone.startswith('0'):
        phone = f'0{phone[3:]}'

    #
    elif phone.startswith('+255') and not phone.startswith('0'):
        phone = f'0{phone[4:]}'
    
    # 
    elif phone.startswith('7') or phone.startswith('6'):
        phone = f'0{phone}'

    # the first three values of the phone:: index 3 in nonincluded
    first_phone = phone[0:3]
    _selected = None
    for _carrier in _carriers.keys():
        # _carrier is a key
        if first_phone in _carriers[_carrier]:
            _selected = _carrier
            break

    return _selected if _selected else ''