In order to make mpld3 work with Python 3.7 the module _display.py has been edited (line 127):

class NumpyEncoder(json.JSONEncoder):
    """ Special json encoder for numpy types """
    def default(self, obj):
        if isinstance(obj, (numpy.int_, numpy.intc, numpy.intp, numpy.int8,
            numpy.int16, numpy.int32, numpy.int64, numpy.uint8,
            numpy.uint16,numpy.uint32, numpy.uint64)):
            return int(obj)
        elif isinstance(obj, (numpy.float_, numpy.float16, numpy.float32, 
            numpy.float64)):
            return float(obj)
        elif isinstance(obj, (numpy.ndarray,)):
            return obj.tolist()
        return json.JSONEncoder.default(self, obj)

In the exporter.py module the following line was edited:

#offset_order = offset_dict[collection.get_offset_position()]

ffset_order = "screen"

