def METHOD_NAME(self, cls):
    # Truncate the value in the repr, since it will
    # typically be very, very large.
    class_name = self.__class__.__name__
    # Return value first like a ValueWidget
    signature = []
    sig_value = 'value={!r}'.format(self.value[:40].tobytes())
    if self.value.nbytes > 40:
        sig_value = sig_value[:-1]+"..."+sig_value[-1]
    signature.append(sig_value)
    for key in super(cls, self)._repr_keys():
        if key == 'value':
            continue
        value = str(getattr(self, key))
        signature.append('{}={!r}'.format(key, value))
    signature = ', '.join(signature)
    return '{}({})'.format(class_name, signature)