What is ideal behavior for band lookups above max value?

[MatthewCaseres]

I think in the past you wanted to return np.nan but then it changed type of array.

Currently it throws an error.

I almost think we shouldn't even throw the error. If someone says 999999 surely they mean np.inf anyways?

What is the best possible behavior?

[lewisfogden]

Some options:

1. raise error if outside bounds
2. automatically convert lower bound to -inf and upper bound to +inf so it covers real line.
3. require users to manually include -inf and +inf with values
4. Let users decide through the type suffix |band_inf etc

I quite like your suggestion i.e. (2), people generally want it to go to inf. (e.g. sum assured >£10m for certain reinsurance)