I know how to do this the other way around... it would be:
>>> dt.rfc822()
'Sun, 09 Mar 1997 13:45:00 -0500'
In [1]: import rfc822 # This only works for python 2 series
In [2]: rfc822.parsedate_tz('Sun, 09 Mar 1997 13:45:00 -0500')
Out[2]: (1997, 3, 9, 13, 45, 0, 0, 1, 0, -18000)
in python3 parsedate_tz has moved to email.utils
>>> import email.utils # this works on Python2.5 and up
>>> email.utils.parsedate_tz('Sun, 09 Mar 1997 13:45:00 -0500')
(1997, 3, 9, 13, 45, 0, 0, 1, -1, -18000)