Strange behaviour of 'is'

[Fijoy George]

Hi all,

I am a bit perplexed by the following behaviour of the 'is' comparator

>>> x = 2.
>>> x is 2.
False
>>> y = [2., 2.]
>>> y[0] is y[1]
True

My understanding was that every literal is a constructure of an object. 
Thus, the '2.' in 'x = 2.' and the '2.' in 'x is 2.' are different objects. 
Therefore, the comparison yields false.

But my understanding does not explain the result of the second comparison. 
According to the experiment, y[0] and y[1] are the same object!

Does anyone know an explanation for this?

Thank you very much
Fijoy