Q:

How to comment out lines with knitr::spin

When using spin in package knitr, how does one simply comment things out to make them invisible to spin?   roxygen style lines (#') are taken as lines to appear in the report.   The usual R comment # is taken as an R comment and appears in a code block.   Lines that are just text, with no special character at the beginning, cause an error.   Lines beginning withe the LaTeX comment % cause an error.   However, plain lines that follow the start of a chunk are taken to be part of the chunk and appear in the code block (#+ or #-).   So is there a character/symbol that functions to mark a comment line in the true sense of the word? 
EDIT: If it has to be invented, the LaTeX comment character % would be quite handy.   Just saying. 

A:

Update: I added the feature of comments for spin() in knitr 1.3.2 (see its Github repos for installation instructions).  Now you can
#' normal text
#' 

# /* a comment here
runif(10)
# and here */

rnorm(5)
#' text continues

Old answer:
That depends on the output format.  For example, for LaTeX, you use %:
#' normal text
#' 
#' % a LaTeX comment here
rnorm(5)
#' text continues

For HTML, it is <!-- -- >:
#' normal text
#' 
#' <!--  an HTML comment here -->
rnorm(5)
#' text continues

