function which(tool, check) {
    return __awaiter(this, void 0, void 0, function* () {
        if (!tool) {
            throw new Error("parameter 'tool' is required");
        }
        // recursive when check=true
        if (check) {
            const result = yield which(tool, false);
            if (!result) {
                if (ioUtil.IS_WINDOWS) {
                    throw new Error(`Unable to locate executable file: ${tool}. Please verify either the file path exists or the file can be found within a directory specified by the PATH environment variable. Also verify the file has a valid extension for an executable file.`);
                }
                else {
                    throw new Error(`Unable to locate executable file: ${tool}. Please verify either the file path exists or the file can be found within a directory specified by the PATH environment variable. Also check the file mode to verify the file is executable.`);
                }
            }
            return result;
        }
        const matches = yield findInPath(tool);
        if (matches && matches.length > 0) {
            return matches[0];
        }
        return '';
    });
}
Returns path of a tool had the tool actually been invoked.  Resolves via paths.
If you check and the tool does not exist, it will throw.

@param     tool              name of the tool
@param     check             whether to check if tool exists
@returns   Promise<string>   path to tool