Merge branch 'stuck_fill' into 'master'

Add stuck_fill lemma.

See merge request !276
6 jobs for master in 13 minutes and 54 seconds (queued for 3 minutes and 16 seconds)
Status Name Job ID Coverage
  Build
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passed build-coq.8.7.2 #34911
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passed build-coq.8.8.2 #34910
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passed build-coq.dev #34906
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