human
Complete this python program:
def addGradientListToDocstring():
assistant
#Here is the Python program you requested.

    """Decorator to add list of current pre-defined gradients to the end of a function docstring.
    """
    def dec(fn):
        if (fn.__doc__ is not None):
            fn.__doc__ = (fn.__doc__ + str(Gradients.keys()).strip('[').strip(']'))
        return fn
    return dec