Finds the the import path from parent node_modules. @see {@link https://github.com/cheton/browserify-css/pull/21} for further information.
function(baseDir, importPath) {
    var parts = importPath.split('/');
    var pathname = path.join(baseDir, importPath);

    if (parts[0] === 'node_modules') {
        // Gets all but the first element of array (i.e. node_modules).
        importPath = parts.slice(1).join('/');
    }

    // Returns an array of all parent node_modules directories.
    var dirs = findNodeModules({
        cwd: baseDir,
        relative: false
    });

    _.each(dirs, function(dir) {
        if (fs.existsSync(path.join(dir, importPath))) {
            pathname = path.join(dir, importPath);
            return false; // Exits iteration by returning false.
        }
    });

    return pathname;
}