eval_src                Eval a character array of code
post_html_render_proc   Post HTML-Rendering Processing
pre_knit_proc           Pre-knitting Processing
preknit_knit_render_postrender
                        First Pre-knitting Processing, then
                        knitr::knit, then rmarkdown::render, then Post
                        HTML-rendering Processing
run_code                Eval a line of code and capture output
