adapted from mpn.scorecard
map_functions_to_scripts(exports_df, pkg_source_path, verbose)A data.frame with the columns `exported_function` and `code_script`.
data.frame with a column, named `exported_function`, containing the names of all exported functions. Can also have other columns (which will be returned unmodified).
a file path pointing to an unpacked/untarred package directory
check for extra information