def METHOD_NAME(assume_installed=True):
    paths = ['/usr/bin/dart', '/usr/lib/dart/bin/dart']
    for path in paths:
        if os.path.exists(path):
            if not assume_installed:
                print('Assumed not installed, found %s' % path)
                sys.exit(1)
        else:
            if assume_installed:
                print('Assumed installed, but could not find %s' % path)
                sys.exit(1)