This function defines a set of web dependencies necessary for using Bootstrap components in a web page.
One of the following:
NULL(the default), which implies a "stock" build of Bootstrap 3.
bslib::bs_theme()object. This can be used to replace a stock build of Bootstrap 3 with a customized version of Bootstrap 3 or higher.
A character string pointing to an alternative Bootstrap stylesheet (normally a css file within the www directory, e.g.