GridLayout how to check if cell is empty?

GridLayout how to check if cell is empty?

Hi and thanks for your help.
I have a GridLayout that I am populating dynamically at runtime.
In order to populate it correctly I need to check if a cell of the grid
has been already populated or not.
Please how do I check if a specific cell (at a specific row and at a
specific column) is empty?
is that even possible?
Thanks for your help!
LISA