ElixirFM::Exec3pm

    use ElixirFM::Exec;                         #   'elixir' will be tried out
    use ElixirFM::Exec '.';                     #   './elixir' will be invoked
    use ElixirFM::Exec './elixir';              #   './elixir' will be invoked
    use ElixirFM::Exec 'some/other';            #   'some/other/elixir' unless
                                                #   'some/other' is executable
    ElixirFM::Exec::elixir 'help';
    import ElixirFM::Exec 'other/elixir';       #   switching to 'other/elixir'
    ElixirFM::Exec::elixir 'inflect', ['(1320,1)'], "V[PI]---3MS--", "N------P-[IRD]";
    ElixirFM::Exec::inflect           ['(1320,1)'], "V[PI]---3MS--", "N------P-[IRD]";