a function or the name of a function. It determines how
where the HTML code is directed to.
If the working environment is RStudio, the default value is
"file.show". In other interactive environments it is
"browser". In non-interactive sessions it is
"stdout".
If output equals "browser" the generated HTML code
is shown using browseURL. If output
equals "stdout" the HTML code is written to the console
output window. If output equals "file.show", the
function file.show is used.
If view_html is called within a Jupyter session,
the HTML code created is envelopped in a pair of <div> tags
and included into the Jupyter output.