I am currently using Linux Mint 19.03 Cinnamon.
Issue
I launch gnome-calculator with Cal shortcut button and when I press that button, new gnome-calculator window is spawned. I don't want this behaviour.

Expected result
I am expecting the Cal button launches gnome-calculator but if it is already running, when Cal is pressed again, it will reveal the existing window, and so on and so forth.
Current attempt
I've found, using dconf editor that I can customize the desktop.
So far, I've also found the string to execute the gnome-calculator which is:
org.cinnamon.desktop.default-applications.calculator exec 'gnome-calculator'
I use dconf editor such as this one:

So far, what I need is to change the Custom value with the proper command to check the existing calculator window and reveal it.
The question
What is the command (or script too) to focus on existing gnome-calculator window? And if it doesn't exist, simply spawn one.
Thank you in advance.
wmctrlutility, and 2) GTK options.