Disable input widget or mark it as unused?

I have a node, which implements the relationship

    a = b * c * d

Then I can write 3 additional nodes, which calculate

    b = a / (c * d)
    c = a / (b * d)
    d = a / (b * c)

So far so good. But it’s also very unwieldy.

Another approach is to have just one node, where the first input is of dtypes.Choice(items=['a', 'b', 'c', 'd']), which selects which variable will be calculated.

Now there are two routes concerning the input:

1. Have three inputs and change the label_str accordingly. This works perfectly.
2. Have four inputs and use only those, which are needed. This also works fine, but it would be nice to have a visual indicator to mark the unused input.

How would I disable an input widget or mark it as unused?

[sphh]

The workaround works perfectly, but I leave this issue open, because it refers to the feature request of disabling the whole input. I hope, this is ok.

[sphh]

Excellent! That’s that one I was looking for. Thanks.