The base class for all stepsSource:
Override this class to create a new step.
This method must be overridden, it is called when running the stage to which a step has been added.
This is just a placeholder.
This method is called when preparing the stage to
which a step has been added. It auto-install all packages which are
needed for a certain step. For example,
the pkgdown package.
add_code_step(), it autodetects any package calls in the form of
pkg::fun and tries to install these packages from CRAN. If a steps
prepare_call is not empty, the
$prepare method is skipped for this
step. This can be useful if a package should be installed from
non-standard repositories, e.g. from GitHub.