How to send an argument to a slot program

Let me explain
I want to get a list of (reduced) words in a dictionary
like for example:
all words starting with ‘ant’
i created a test program in slot_program named ‘test’ such as:

#! / usr / bin / env sh
echo “$1”

my sentence is

display ($ test,<word>) {item}

who should return the argument to me
and I ask to recognize:

the sentece is :

display arg1

and I would like to have in return

item = arg1

in fact this is what I would like to do but how to finalize this

another question how to take the ‘x’ first letters of the entry

Thank you

Nobody can help me ?