(WIP) implementing CBD language... Meta-meta-model: Association inherits from Class. Matcher accepts pivot. Add generic graphviz renderer.

util/eval.py

@@ -0,0 +1,9 @@
+# based on https://stackoverflow.com/a/39381428
+# Parses and executes a block of Python code, and returns the eval result of the last statement
+import ast
+def exec_then_eval(code, _globals, _locals):
+    block = ast.parse(code, mode='exec')
+    # assumes last node is an expression
+    last = ast.Expression(block.body.pop().value)
+    exec(compile(block, '<string>', mode='exec'), _globals, _locals)
+    return eval(compile(last, '<string>', mode='eval'), _globals, _locals)