Is there an easy way to specify the python version to use for a particular block or sub-tree?

My use case is that I have mainly migrated to python 3, but there is still the occasional library that has not been updated yet, so I need to fall back to python 2.7 for some tasks.

I can work around the problem by putting the python 2 code in a separate org file and use

# Local Variables:

# org-babel-python-command: "/path/to/python2"

# End:

but keeping everything in the same file would be preferable.

Thanks

Will

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Dr William Henney, Centro de Radioastronomía y Astrofísica,
Universidad Nacional Autónoma de México, Campus Morelia