def normalizeTransformationMatrix(value):
    """
    Normalizes transformation matrix.

    * **value** must be an ``tuple`` or ``list``.
    * **value** must have exactly six items. Each of these
      items must be an instance of :ref:`type-int-float`.
    * Returned value is a ``tuple`` of six ``float``.
    """
    if not isinstance(value, (tuple, list)):
        raise TypeError("Transformation matrices must be tuple instances, "
                        "not %s." % type(value).__name__)
    if not len(value) == 6:
        raise ValueError("Transformation matrices must contain six values, "
                         "not %d." % len(value))
    for v in value:
        if not isinstance(v, (int, float)):
            raise TypeError("Transformation matrix values must be instances "
                            "of :ref:`type-int-float`, not %s."
                            % type(v).__name__)
    return tuple([float(v) for v in value])