Verify a provided client id against the database and set the `Client` object that is
        associated with it to `self.client`.

        TODO: Document all of the thrown exceptions.

def verify_client_id(self):
        """
        Verify a provided client id against the database and set the `Client` object that is
        associated with it to `self.client`.

        TODO: Document all of the thrown exceptions.
        """

        from .models import Client
        from .exceptions.invalid_client import ClientDoesNotExist
        from .exceptions.invalid_request import ClientNotProvided

        if self.client_id:
            try:
                self.client = Client.objects.for_id(self.client_id)
            # Catching also ValueError for the case when client_id doesn't contain an integer.
            except (Client.DoesNotExist, ValueError):
                raise ClientDoesNotExist()
        else:
            raise ClientNotProvided()