adding ai_economist for modding

ai_economist/foundation/entities/endogenous.py

@@ -0,0 +1,36 @@
+# Copyright (c) 2020, salesforce.com, inc.
+# All rights reserved.
+# SPDX-License-Identifier: BSD-3-Clause
+# For full license text, see the LICENSE file in the repo root
+# or https://opensource.org/licenses/BSD-3-Clause
+
+from ai_economist.foundation.base.registrar import Registry
+
+
+class Endogenous:
+    """Base class for endogenous entity classes.
+
+    Endogenous entities are those that, conceptually, describe the internal state
+    of an agent. This provides a convenient way to separate physical entities (which
+    may exist in the world, be exchanged among agents, or are otherwise in principal
+    observable by others) from endogenous entities (such as the amount of labor
+    effort an agent has experienced).
+
+    Endogenous entities are registered in the "endogenous" portion of an agent's
+    state and should only be observable by the agent itself.
+    """
+
+    name = None
+
+    def __init__(self):
+        assert self.name is not None
+
+
+endogenous_registry = Registry(Endogenous)
+
+
+@endogenous_registry.add
+class Labor(Endogenous):
+    """Labor accumulated through working. Included in all environments by default."""
+
+    name = "Labor"