Heartbeat also using block_until_complete().

examples/heartbeat_demo/alicia.py

@@ -141,6 +141,7 @@ policy = alicia.grant(bob=doctor_strange,
                       m=m,
                       n=n,
                       expiration=policy_end_datetime)
+policy.publishing_mutex.block_until_complete()
 print("Done!")
 
 # For the demo, we need a way to share with Bob some additional info

nucypher/policy/policies.py

@@ -14,7 +14,7 @@ GNU Affero General Public License for more details.
 You should have received a copy of the GNU Affero General Public License
 along with nucypher.  If not, see <https://www.gnu.org/licenses/>.
 """
-
+import math
 import time
 import random
 from abc import ABC, abstractmethod