sets/gets given folder path if provided else checks in order:
path.expand("~") (tilde (~) expands to HOME folder path)
Sys.getenv("R_USER") (set on R session start)
Sys.getenv("USERPROFILE") (Windows specific)
get_base_folder(folder_path = NULL)character folder path
get_base_folder()
#> [1] "C:/Users/Home/Documents"