def check_using_namespace(lines):
    index = [i for (i, s) in enumerate(lines) if ('using namespace' in s.strip())]
    if (len(index) > 0):
        return lines[index[0]]
    else:
        return ''
def check_using_namespace(lines):
    index = [i for (i, s) in enumerate(lines) if ('using namespace' in s.strip())]
    if (len(index) > 0):
        return lines[index[0]]
    else:
        return 