Sprint 2 Step 7: Schema validation

docs/BuildCacheExample.md

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+# Building a Cache - Whetstone AST (Canonical Form)
+
+```
+Function: getOrCreate
+  @deref(???)
+  Parameter: cache -> Map<string, Widget>
+  Parameter: key -> string
+  Body:
+    IfStatement:
+      condition: key in cache
+      then: Return cache[key]
+      else:
+        Assignment: widget = Widget.create(key)
+        Assignment: cache[key] = widget
+        Return: widget
+```