EN in keymap MAP.
     Equivalent to 'rl_function_of_keyseq' with the addition of the LEN
     parameter.  It takes a "translated" key sequence and should be used
     if the key sequence can include NUL.

 -- Function: int rl_trim_arg_from_keyseq (const char *keyseq, size_t
          len, Keymap map)
     If there is a numeric argument at the beginning of KEYSEQ, possibly
     including digits, return the index of the first character in KEYSEQ
     following the numeric argument.  This can be used to skip over the
     numeric argument (which is available as 'rl_numeric_arg' while
     traversing the key sequence that invoked the current command.

 -- Function: char ** rl_invoking_keyseqs (rl_command_func_t *function)
     Return an array of strings representing the key sequences used to
     invoke FUNCTION in the current keymap.

 -- Function: char ** rl_invoking_keyseqs_in_map (rl_command_func_t
          *function, Keymap map)
     Return an array of strings representing the key sequences used to
     invoke FUNCTION in the keymap MAP.

 -- Function: void rl_function_dumper (int readable)
     Print the Readline function names and the key sequences currently
     bound to them to 'rl_outstream'.  If READABLE is non-zero, the list
     is formatted in such a way that it can be made part of an 'inputrc'
     file and re-read.

 -- Function: void rl_list_funmap_names (void)
     Print the names of all bindable Readline functions to
     'rl_outstream'.

 -- Function: const char ** rl_funmap_names (void)
     Return a NULL terminated array of known function names.  The array
     is sorted.  The array itself is allocated, but not the strings
     inside.  You should free the array, but not the pointers, using
     'free' or 'rl_free' when you are done.

 -- Function: int rl_add_funmap_entry (const char *name,
          rl_command_func_t *function)
     Add NAME to the list of bindable Readline command names, and make
     FUNCTION the function to be called when NAME is invoked.