help(package = 'YourPackage', help_type = 'html')
# or see a standalone list of vignettes
browseVignettes('YourPackage')

if (TRUE) cat('_hello_ **markdown**!', '\n')

1+1
10:1
rnorm(5)^2
strsplit('hello, markdown vignettes', '')

n=300; set.seed(123)
par(mar=c(4,4,.1,.1))
plot(rnorm(n), rnorm(n), pch=21, cex=5*runif(n), col='white', bg='gray')