basics on homotopy cofibers #3337

Job	Run time
build (supported)	3m 30s
opam-build (supported, ubuntu-latest)	5m 9s
build (latest)	3m 27s
nix	2m 28s
opam-build (latest, ubuntu-latest)	4m 27s
quick-build (supported, ubuntu-latest)	3m 14s
build (dev, --warnings)	2m 52s
opam-build (dev, ubuntu-latest)	3m 20s
quick-build (latest, ubuntu-latest)	3m 14s
quick-build (dev, ubuntu-latest)	2m 45s
doc-coqdoc	0s
coqchk	0s
doc-dep-graphs	0s
doc-alectryon	0s
doc-timing	0s
install	0s
deploy-doc	0s
delete-artifacts	4s
	34m 30s

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