Add bounded int docstring template to class init.

def _bounded_int_doc(cls):
    """Add bounded int docstring template to class init."""
    def __init__(self, value=None, min=None, max=None, step=None, **kwargs):
        if value is not None:
            kwargs['value'] = value
        if min is not None:
            kwargs['min'] = min
        if max is not None:
            kwargs['max'] = max
        if step is not None:
            kwargs['step'] = step
        super(cls, self).__init__(**kwargs)

    __init__.__doc__ = _bounded_int_doc_t
    cls.__init__ = __init__
    return cls