Serialize given datas to a flat structure ``KEY:VALUE`` where ``KEY``
        comes from ``keys`` variable and ``VALUE`` comes from ``values``
        variable.

        This means both ``keys`` and ``values`` are required variable to be
        correctly filled (each one is a string of item separated with an empty
        space). Both resulting list must be the same length.

        Arguments:
            name (string): Name only used inside possible exception message.
            datas (dict): Datas to serialize.

        Returns:
            dict: Flat dictionnay of serialized reference datas.

def serialize_to_flat(self, name, datas):
        """
        Serialize given datas to a flat structure ``KEY:VALUE`` where ``KEY``
        comes from ``keys`` variable and ``VALUE`` comes from ``values``
        variable.

        This means both ``keys`` and ``values`` are required variable to be
        correctly filled (each one is a string of item separated with an empty
        space). Both resulting list must be the same length.

        Arguments:
            name (string): Name only used inside possible exception message.
            datas (dict): Datas to serialize.

        Returns:
            dict: Flat dictionnay of serialized reference datas.
        """
        keys = datas.get('keys', None)
        values = datas.get('values', None)
        splitter = datas.get('splitter', self._DEFAULT_SPLITTER)

        if not keys:
            msg = ("Flat reference '{}' lacks of required 'keys' variable or "
                   "is empty")
            raise SerializerError(msg.format(name))
        else:
            keys = self.value_splitter(name, 'keys', keys, mode=splitter)

        if not values:
            msg = ("Flat reference '{}' lacks of required 'values' variable "
                   "or is empty")
            raise SerializerError(msg.format(name))
        else:
            values = self.value_splitter(name, 'values', values, mode=splitter)

        if len(values) != len(keys):
            msg = ("Flat reference have different length of 'keys' ands "
                   "'values' variable")
            raise SerializerError(msg.format(name))

        return OrderedDict(zip(keys, values))