virtualEnvironment/lib/python2.7/site-packages/coverage/misc.py
def expensive(fn):
    """A decorator to cache the result of an expensive operation.

    Only applies to methods with no arguments.

    """
    attr = "_cache_" + fn.__name__
    def _wrapped(self):
        """Inner fn that checks the cache."""
        if not hasattr(self, attr):
            setattr(self, attr, fn(self))
        return getattr(self, attr)
    return _wrapped
def expensive(fn):
    """A decorator to cache the result of an expensive operation.

    Only applies to methods with no arguments.

    """
    attr = "_cache_" + fn.__name__
    def _wrapped(self):
        """Inner fn that checks the cache."""
        if not hasattr(self, attr):
            setattr(self, attr, fn(self))
        return getattr(self, attr)
    return _wrapped
A decorator to cache the result of an expensive operation.

    Only applies to methods with no arguments.