Use the [`usage`](https://developers.google.com/code-search/reference#filters) filter to search for a use while
excluding comments and string literals. For example, the following search
returns all functions with the term `main`.

    usage:main

Like a simple search for `main`, a `usage:main` search finds

    int main(void)

But unlike a search for `main`, a `usage:main` search ignores

    // The main thing here

and

    myvar = "The main class."