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