def is_delivered(a_promise):
"""
True if `a_promise` is a promise and has been delivered
"""
return is_proxy_delivered(a_promise) if is_proxy(a_promise) \
else a_promise.is_delivered()
def is_promise(obj):
"""
True if `obj` is a promise (either a proxy or a container)
"""
return (is_proxy(obj) or \
(hasattr(obj, "is_delivered") and
hasattr(obj, "deliver")))
def deliver(on_promise):
"""
Attempts to deliver on a promise, and returns the resulting
value. If the delivery of work causes an exception, it will be
raised here.
Parameters
----------
on_promise : `Proxy` or `Container` promise
the promise to deliver on
Returns
-------
value
the promised work if it could be successfully computed
"""
return deliver_proxy(on_promise) if is_proxy(on_promise) \
else on_promise.deliver()
