Applying the suggestions by @veroandreo in #68 (weren't yet accepted -> committed in that pull request).
coerce.Rmd: since the vignette serves the educational purpose, 9563916 suggests to promote library() for loading and attaching the packages and hides the logic of checking the package existance from the user, using requireNamespace() there.
coerce.Rmd: since the vignette serves the educational purpose, 9563916 suggests to promotelibrary()for loading and attaching the packages and hides the logic of checking the package existance from the user, usingrequireNamespace()there.