Autonomous Python Script

[Leyo]

good evening,

May I ask for your help again?

Create a plural.py script, capable of taking several words and displaying their plural.

Example:

$several.py dog, cat, bird
dogs
cats
birds

The script must be used in the terminal.

so far I wrote:

def several(a,b,c):
    plural_a=a+'s'
    plural_b=b+'s'
    plural_c=c+'s'

    print( plural_a+"\n",plural_b+"\n",plural_c+"\n")
several('cat','dog','camel')

And it works.
but somehow I can't launch it from my terminal.
I'm on Ubuntu.
the script is in the main directory
I used chmod +x several.py to make the script executable from the terminal
yet nothin happens -> is my script wrong?