Verification using selectors occasionally requires a call to SteelSel.get

[R1kM]

In some cases, SMT verification of selectors VCs requires the global selector in the context. For instance: https://github.com/FStarLang/FStar/blob/c751ed5db01a24c13e334bab2c5762389a34791b/examples/steel/Selectors.LList.Derived.fst#L11

The most probable cause is that refinements on the types of selectors prevent SMT triggering.
We need to look in detail at generated SMT queries.

In the meantime, a workaround is to add let h = get ... at different points of the program (usually mostly at the very beginning) when SMT verification fails.