#' These functions can be used to predefine your own reference to be used in \code{\link{as.mo}} and consequently all \code{mo_*} functions like \code{\link{mo_genus}} and \code{\link{mo_gramstain}}.
#' @param path location of your reference file, see Details
#' @rdname mo_source
#' @name mo_source
#' @aliases set_mo_source get_mo_source
#' @details The reference file can be a text file seperated with commas (CSV) or pipes, an Excel file (old 'xls' format or new 'xlsx' format) or an R object file (extension '.rds'). To use an Excel file, you need to have the \code{readxl} package installed.
#'
#' \code{set_mo_source} will check the file for validity: it must be a \code{data.frame}, must have a column named \code{"mo"} which contains values from \code{microorganisms$mo} and must have a reference column with your own defined values. If all tests pass, \code{set_mo_source} will read the file into R and export it to \code{"~/.mo_source.rds"}. This compressed data file will then be used at default for MO determination (function \code{\link{as.mo}} and consequently all \code{mo_*} functions like \code{\link{mo_genus}} and \code{\link{mo_gramstain}}). The location of the original file will be saved as option with \code{\link{options}(mo_source = path)}. Its timestamp will be saved with \code{\link{options}(mo_source_datetime = ...)}.
#'
#' \code{get_mo_source} will return the data set by reading \code{"~/.mo_source.rds"} with \code{\link{readRDS}}. If the original file has changed (the file defined with \code{path}), it will call \code{set_mo_source} to update the data file automatically.
#'
#' Reading an Excel file (\code{.xlsx}) with only one row has a size of 8-9 kB. The compressed file will have a size of 0.1 kB and can be read by \code{get_mo_source} in only a couple of microseconds (a millionth of a second).
#' @importFrom dplyr select everything
#' @export
#' @inheritSection AMR Read more on our website!
#' @examples
#' \dontrun{
#'
#' # imagine this Excel file (mo codes looked up in `microorganisms` data set):
#' # A B
#' # 1 our code mo
#' # 2 lab_mo_ecoli B_ESCHR_COL
#' # 3 lab_mo_kpneumoniae B_KLBSL_PNE
#'
#' # 1. We save it as 'home/me/ourcodes.xlsx'
#'
#' # 2. We use it for input:
#' set_mo_source("C:\path\ourcodes.xlsx")
#' #> Created mo_source file '~/.mo_source.rds' from 'home/me/ourcodes.xlsx'.
#'
#' # 3. And use it in our functions:
#' as.mo("lab_mo_ecoli")
#' #> B_ESCHR_COL
#'
#' mo_genus("lab_mo_kpneumoniae")
#' #> "Klebsiella"
#'
#' # 4. It will look for changes itself:
#' # (add new row to the Excel file and save it)
#'
#' mo_genus("lab_mo_kpneumoniae")
#' #> Updated mo_source file '~/.mo_source.rds' from 'home/me/ourcodes.xlsx'.