How to use count prefix in custom keybindings?

This might end up being a feature request but atm I just don't know if I'm missing something.

I made the following keybinding for commenting a line:

    "vim.normalModeKeyBindings": [
        {
            "before": ["<leader>", "c", "l"],
            "commands": ["editor.action.commentLine"]
        }
    ]

It works for a single line, and I expected eg 3 <leader> c l to comment 3 lines but instead nothing happens. Do I need to capture the count prefix in the keybinding definition? or something else?

Reproduce the custom keybinding from the issue in VSCodeVim, comparing a single-line invocation with 3 <leader> c l. Start by tracing how vim.normalModeKeyBindings handles count prefixes; done means determining whether counts are supported for custom commands and documenting or implementing the expected behavior.