Invisibly, the (potentially concatenated) input as character
vector.
Arguments
input
Either a data.frame, table, or matrix,
or a list with three elements: pre, input, and post.
The pre and post are simply prepended and postpended to
the HTML generated based on the input$input element.
output
The output: a character vector with one or more
of "console" (the raw concatenated input, without conversion
to HTML), "viewer", which uses the RStudio viewer if available,
and one or more filenames in existing directories.