diff --git a/llpython/addr_flow.py b/llpython/addr_flow.py
index 7447789..8630a5a 100644
--- a/llpython/addr_flow.py
+++ b/llpython/addr_flow.py
@@ -5,6 +5,7 @@
 from __future__ import absolute_import
 
 from .byte_flow import BytecodeFlowBuilder
+from .opcode_util import build_basic_blocks, itercodeobjs
 
 # ______________________________________________________________________
 # Class definition(s)
@@ -79,16 +80,43 @@ def build_addr_flow(func):
     cfg = byte_control.build_cfg(func)
     return AddressFlowBuilder().visit_cfg(cfg)
 
+# ______________________________________________________________________
+
+def build_addr_flow_from_co(codeobj):
+    from .byte_control import ControlFlowBuilder
+    cfg = ControlFlowBuilder().visit(build_basic_blocks(codeobj),
+                                     codeobj.co_argcount)
+    return AddressFlowBuilder().visit_cfg(cfg)
+
+# ______________________________________________________________________
+
+def build_addr_flows_from_co(root_co):
+    return dict((co, build_addr_flow_from_co(co))
+                for co in itercodeobjs(root_co))
+
 # ______________________________________________________________________
 # Main (self-test) routine
 
 def main(*args):
     import pprint
-    from .tests import llfuncs
+    try:
+        from .tests import llfuncs
+    except ImportError:
+        llfuncs = object()
     if not args:
         args = ('pymod',)
     for arg in args:
-        pprint.pprint(build_addr_flow(getattr(llfuncs, arg)))
+        if arg.endswith('.py'):
+            with open(arg) as in_file:
+                in_source = in_file.read()
+                in_codeobj = compile(in_source, arg, 'exec')
+                flow_map = build_addr_flows_from_co(in_codeobj)
+                for codeobj, flow in flow_map.items():
+                    print("_" * 70)
+                    print(codeobj)
+                    pprint.pprint(flow)
+        else:
+            pprint.pprint(build_addr_flow(getattr(llfuncs, arg)))
 
 # ______________________________________________________________________
 
diff --git a/llpython/opcode_util.py b/llpython/opcode_util.py
index bec9c01..b6ccf11 100644
--- a/llpython/opcode_util.py
+++ b/llpython/opcode_util.py
@@ -1,9 +1,10 @@
 #! /usr/bin/env python
 # ______________________________________________________________________
 
+from collections import namedtuple
 import dis
 import opcode
-from collections import namedtuple
+import types
 
 # ______________________________________________________________________
 # Module data
@@ -195,6 +196,16 @@ def itercode(code, start = 0):
 
 # ______________________________________________________________________
 
+def itercodeobjs(codeobj):
+    "Iterator that traverses code objects via the co_consts member."
+    yield codeobj
+    for const in codeobj.co_consts:
+        if isinstance(const, types.CodeType):
+            for childobj in itercodeobjs(const):
+                yield childobj
+
+# ______________________________________________________________________
+
 def extendlabels(code, labels = None):
     """Extend the set of jump target labels to account for the
     passthrough targets of conditional branches.