check_args              Assert none of the arguments of a function are
                        null.
fix_column_names        fix_column_names
fix_names               fix_names
kable                   Create tables in LaTeX, HTML, Markdown and
                        reStructuredText
load_opts               Setting/loading and extracting various options
                        into the environment
opts                    default opts
parse_opts              Parse options to expand '{{variable}}' into
                        their respective values
read_sheet              Read/Write sheets (automatically detect the
                        file type and work accordingly)
