TypeError: unhashable type: 'dict' when attempting to hash list - advice sought

[Laura Creighton]

When you get TypeError: unhashable type: 'dict'
it almost always means that you are trying to use a dict as
a key for a different dict.


Python 2.7.10 (default, Jul  1 2015, 10:54:53)
[GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> d={1:'one', 2:'two', 3:'three'}
 >>> d1={1:'A', 2:'B', 3:'C'}

 This doesn't work.
 
 >>> print d1[d]
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
 TypeError: unhashable type: 'dict'

This does.

 >>> for index in d:
   ...     print d1[index]
   ...
   A
   B
   C

HTH,
Laura