@classmethod
def _constructor(cls, values, axes, **metadata):
    """ Internal API for the constructor: check whether a pre-defined class exists

        values        : array-like
        axes        : Axes instance 

        This static method is used whenever a new DimArray needs to be instantiated
        for example after a transformation.

        This makes the sub-classing process easier since only this method needs to be 
        overloaded to make the sub-class a "closed" class.

        """
    return cls(values, axes, **metadata)
