python - Python- import ipdb が失敗する

Question

Python Debugger を使用しようとしています。

ここで何がうまくいかないのかわかりません。

def main():
    print "over ipdb"
    import ipdb; ipdb.set_trace()
    low, high = 0, 1
    for i in xrange(10):
        print high
        low, high = high, low + high

if __name__ == '__main__':
  main()

端末はこれを表示し続けます：

over ipdb
Before the function runs
I am a stand alone function, don't you dare modify me
After the function runs
Traceback (most recent call last):
  File "pydebudder.py", line 12, in <module>
    main()
  File "pydebudder.py", line 5, in main
    import ipdb; ipdb.set_trace()
  File "/usr/local/lib/python2.7/dist-packages/ipdb/__init__.py", line 16, in <module>
    from ipdb.__main__ import set_trace, post_mortem, pm, run, runcall, runeval, launch_ipdb_on_exception
  File "/usr/local/lib/python2.7/dist-packages/ipdb/__main__.py", line 27, in <module>
    import IPython
  File "/usr/local/lib/python2.7/dist-packages/IPython/__init__.py", line 45, in <module>
    from .config.loader import Config
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/__init__.py", line 6, in <module>
    from .application import *
  File "/usr/local/lib/python2.7/dist-packages/IPython/config/application.py", line 17, in <module>
    from IPython.external.decorator import decorator
ImportError: cannot import name decorator

ipython を 3.0.0 にアップグレードしました