'Get the prefix of an account
Determines which reseller prefix matches the account and returns
that prefix. If account does not start with one of the known
reseller prefixes, returns None.
:param account: Account name (e.g., AUTH_joesaccount) or None
:return: The prefix string (examples: \'AUTH_\', \'SERVICE_\', \'\')
If we can\'t match the prefix of the account, return None'

def _get_account_prefix(self, account):

    if (account is None):
        return None
    for prefix in self._non_empty_reseller_prefixes():
        if account.startswith(prefix):
            return prefix
    if ('' in self.reseller_prefixes):
        return ''
    return None
