human
Write me a Python code to print "sys not found" given the following:
Complete the below
@contextmanager
def mask_modules(*modnames):

    ''''Ban some modules from being importable inside the context
    For example:
    >>> with missing_modules("sys"):
    ...     try:
    ...         import sys
    ...     except ImportError:
    ...         print "sys not found"
    sys not found
    >>> import sys
    >>> sys.version
    (2, 5, 2, \'final\', 0)'
    '''
assistant
#Here is Python code to print "sys not found"
.
    realimport = builtins.__import__
    def myimp(name, *args, **kwargs):
        if (name in modnames):
            raise ImportError(('No    module    named    %s' % name))
        else:
            return realimport(name, *args, **kwargs)
    builtins.__import__ = myimp
    (yield True)
    builtins.__import__ = realimport