includes2() is a version of the includes() helper function from rmarkdown
that uses yml_blank() instead of NULL as the argument defaults, as
ymlthis treats NULLs as literal YAML syntax ("null").
a list
# \donttest{
yml() %>%
yml_output(
pdf_document(includes = includes2(after_body = "footer.tex"))
)
#> ---
#> date: '`r format(Sys.Date())`'
#> output:
#> pdf_document:
#> includes:
#> after_body: footer.tex
#> ---
#>
# }