@interactive
def _require(*names):
    """Helper for @require decorator."""
    from IPython.parallel.error import UnmetDependency
    user_ns = globals()
    for name in names:
        if name in user_ns:
            continue
        try:
            exec('import %s'%name, user_ns)
        except __HOLE__:
            raise UnmetDependency(name)
    return True
dataset/ETHPy150Open ipython/ipython-py3k/IPython/parallel/controller/dependency.py/_require