#' @param .how The function(s) or function call(s) that will perform the transformation. If many,
#'   a list should be used, either with `list()` or `.()`. If the list is named, the names will be
#'   used for the new columns' names. Lambdas specified as formulas are supported.
#' @param ... Possibly more arguments for *all* functions/calls in `.how`.
