Add usage example in Readme

README.rst

@@ -20,9 +20,29 @@ Usage
 
 .. code-block:: python
 
-    import asdl
+    from asdl import ASDLParser, parse
+
+    syntax = """
+        module Lambda {
+            term =
+                Lambda(name x, term body) |
+                Apply(term function, term argument) |
+                Variable(name x)
+        }
+    """
+
+    print(ASDLParser().parse(syntax))
+
     print(asdl.parse("./test/Python.asdl"))
 
+Output:
+
+.. code-block::
+
+    Module(Lambda, [Type(term, Sum([Constructor(Lambda, [Field(name, x), Field(term, body)]), Constructor(Apply, [Field(term, function), Field(term, argument)]), Constructor(Variable, [Field(name, x)])]))])
+
+    Module(Python, [Type(mod, Sum([Constructor(Module, [Field(stmt, body, seq=True)]), Constructor(Interactive, [Field(stmt, body, seq=True)]), Constructor(Expression, [Field(expr, body)]), Constructor(Suite, ...
+
 
 License
 -------

test/Lambda.asdl

@@ -0,0 +1,6 @@
+module Lambda {
+    term =
+        Lambda(name x, term body) |
+        Apply(term function, term argument) |
+        Variable(name x)
+}

test/test_asdl.py

@@ -1,4 +1,4 @@
-"""Tests for the asdl parser in Parser/asdl.py"""
+"""Tests for the asdl parser in asdl.py"""
 
 import os
 import unittest