in setting.json

{
    "before": ["g", "x"],
    "after": [],
    "commands": [
        {
            "command": "extension.openBrowser",
            "args": []
        }
    ]
},
{
    "before": ["g", "y"],
    "after": [],
    "commands": [
        {
            "command": "extension.yewSyntax",
            "args": []
        }
    ]
}

Q: Where are extensions installed?

A: Extensions are installed in a per user extensions folder. Depending on your platform, the location is in the following folder:

• Windows %USERPROFILE%\.vscode\extensions
• macOS ~/.vscode/extensions
• Linux ~/.vscode/extensions

You can change the location by launching VS Code with the --extensions-dir <dir> command line option.