>>> l = [ 1, 1, 4, 3, 2, 2, 2, 5, 5, 6 ]
>>> l
Out[3]: [1, 1, 4, 3, 2, 2, 2, 5, 5, 6]
>>> len(l)
Out[4]: 10
>>> sl = set(l)
>>> len(sl)
Out[6]: 6
>>> sl
Out[7]: set([1, 2, 3, 4, 5, 6])
>>> sl[0]
Traceback (most recent call last):
  File "/Users/rcd/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/IPython/core/interactiveshell.py", line 2721, in run_code
    exec code_obj in self.user_global_ns, self.user_ns
  File "<ipython-input-8-75fccc50700a>", line 1, in <module>
    sl[0]
TypeError: 'set' object does not support indexing

>>> l0 = [ 0 ] * 10
>>> l0
Out[10]: [0,0,0,0,0,0,0,0,0,0]
>>> len(l0)
Out[11]: 100
>>> set(l0)
Out[12]: set([0])
>>> len(set(l0))
Out[13]: 1
>>> print(set(l0))
set([0])

>>> ll = [ [1, 1, 1], [1, 1, 1], [2, 2, 2] ]
>>> len(ll)
Out[16]: 3
>>> set(ll)
Traceback (most recent call last):
  File "/Users/rcd/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/IPython/core/interactiveshell.py", line 2721, in run_code
    exec code_obj in self.user_global_ns, self.user_ns
  File "<ipython-input-17-25f0de3d3955>", line 1, in <module>
    set(ll)
TypeError: unhashable type: 'list'
>>> tl = [ (1, 1, 1), (1, 1, 1), (2, 2, 2) ]
>>> len(tl)
Out[19]: 3
>>> tl[0]
Out[20]: (1, 1, 1)
>>> tl[0][0]
Out[21]: 1
>>> type(tl[0])
Out[22]: tuple
>>> tl[0] += tuple([3])
>>> tl[0] = tl[0] + tuple([3])
>>> tl
Out[33]: [(1, 1, 1, 3, 3), (1, 1, 1), (2, 2, 2)]
>>> st = set(tl)
>>> st
Out[35]: set([(2, 2, 2), (1, 1, 1), (1, 1, 1, 3, 3)])