I managed to run into 2 trying to build a 5 line program :-)

  $ cat t.py; ./tools/grumpc t.py  > t.go;go build t.go;echo '----';./t
  import sys
  print sys.stdin.readline()
  ----
  AttributeError: 'module' object has no attribute 'stdin'
  $

  $ cat t.py ;./tools/grumpc t.py
  c = {}
  top = sorted(c.items(), key=lambda (k,v): v)
  Traceback (most recent call last):
    File "./tools/grumpc", line 102, in <module>
      sys.exit(main(parser.parse_args()))
    File "./tools/grumpc", line 60, in main
      visitor.visit(mod)
    File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ast.py", line 241, in visit
      return visitor(node)
    File "/Users/foo/src/grumpy/build/lib/python2.7/site-packages/grumpy/compiler/stmt.py", line 302, in visit_Module
      self._visit_each(node.body)
    File "/Users/foo/src/grumpy/build/lib/python2.7/site-packages/grumpy/compiler/stmt.py", line 632, in _visit_each
      self.visit(node)
    File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ast.py", line 241, in visit
      return visitor(node)
    File "/Users/foo/src/grumpy/build/lib/python2.7/site-packages/grumpy/compiler/stin visit_Assign
      with self.expr_visitor.visit(node.value) as value:
    File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ast.py", line 241, in visit
      return visitor(node)
    File "/Users/foo/src/grumpy/build/lib/python2.7/site-packages/grumpy/compiler/expr_visitor.py", line 101, in visit_Call
      values.append((util.go_str(k.arg), self.visit(k.value)))
    File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ast.py", line 241, in visit
      return visitor(node)
    File "/Users/foo/src/grumpy/build/lib/python2.7/site-packages/grumpy/compiler/expr_visitor.py", line 246, in visit_Lambda
      return self.visit_function_inline(func_node)
    File "/Users/foo/src/grumpy/build/lib/python2.7/site-packages/grumpy/compiler/expr_visitor.py", line 388, in visit_function_inline
      func_visitor = block.FunctionBlockVisitor(node)
    File "/Users/foo/src/grumpy/build/lib/python2.7/site-packages/grumpy/compiler/block.py", line 432, in __init__
      args = [a.id for a in node_args.args]
  AttributeError: 'Tuple' object has no attribute 'id'