diff --git a/juju/client/codegen.py b/juju/client/codegen.py
new file mode 100644
index 0000000..f8a792a
--- /dev/null
+++ b/juju/client/codegen.py
@@ -0,0 +1,52 @@
+from collections import defaultdict
+from io import StringIO
+from textwrap import indent
+
+
+class CodeWriter(StringIO):
+    """
+    Blob of text that, when used in the context of facade.py, ends up
+    holding the source code for a Python class and associated methods.
+
+    """
+    INDENT = "    "
+
+    CLASS = 0
+    METHOD = 1
+
+    def write(self, msg, depth=0):
+        if depth:
+            prefix = self.INDENT * depth
+            msg = indent(msg, prefix)
+
+        return super(CodeWriter, self).write(msg)
+
+    def __str__(self):
+        return super(CodeWriter, self).getvalue()
+
+
+class Capture(defaultdict):
+    """
+    A collection of CodeWriter objects, together representing a Python
+    module.
+
+    """
+
+    def __init__(self, default_factory=CodeWriter, *args, **kwargs):
+        super(Capture, self).__init__(default_factory, *args, **kwargs)
+
+    def clear(self, name):
+        """
+        Reset one of the keys in this class, if it exists.
+
+        This is necessary, because we don't worry about de-duplicating
+        the schemas for each version of juju up front, and this gives
+        us a way to sort of de-duplicate on the fly, by resetting a
+        specific CodeWriter instance before we start to write a class
+        into it.
+
+        """
+        try:
+            del self[name]
+        except KeyError:
+            pass