What’s a good way to estimate option liquidity throughout the day?

I'm writing up an algorithm for some option trading and I'm not sure what the best way to gauge option liquidity is; for instance, if liquidity is low, you might not want to buy too many of that contract, because you won't be able to sell them at the price you want very quickly (or at all!)

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Is there any metric for measuring/estimating this, or should I just go crazy with trying to make up my own way to estimate option liquidity for my algo?