Add initial postprocess unit test thingy.

recipe_engine/third_party/astunparse/printer.py

Index: recipe_engine/third_party/astunparse/printer.py
diff --git a/recipe_engine/third_party/astunparse/printer.py b/recipe_engine/third_party/astunparse/printer.py
new file mode 100644
index 0000000000000000000000000000000000000000..92d64f772bff92956f71aa41b806f9f57d074d04
--- /dev/null
+++ b/recipe_engine/third_party/astunparse/printer.py
@@ -0,0 +1,51 @@
+from __future__ import unicode_literals
+import sys
+import ast
+import six
+
+
+class Printer(ast.NodeVisitor):
+
+    def __init__(self, file=sys.stdout, indent="  "):
+        self.indentation = 0
+        self.indent_with = indent
+        self.f = file
+
+    # overridden to make the API obvious
+    def visit(self, node):
+        super(Printer, self).visit(node)
+
+    def write(self, text):
+        self.f.write(six.text_type(text))
+
+    def generic_visit(self, node):
+
+        if isinstance(node, list):
+            nodestart = "["
+            nodeend = "]"
+            children = [("", child) for child in node]
+        else:
+            nodestart = type(node).__name__ + "("
+            nodeend = ")"
+            children = [(name + "=", value) for name, value in ast.iter_fields(node)]
+
+        if len(children) > 1:
+            self.indentation += 1
+
+        self.write(nodestart)
+        for i, pair in enumerate(children):
+            attr, child = pair
+            if len(children) > 1:
+                self.write("\n" + self.indent_with * self.indentation)
+            if isinstance(child, (ast.AST, list)):
+                self.write(attr)
+                self.visit(child)
+            else:
+                self.write(attr + repr(child))
+
+            if i != len(children) - 1:
+                self.write(",")
+        self.write(nodeend)
+
+        if len(children) > 1:
+            self.indentation -= 1