Valence electrons in helium? I am having trouble understanding how valence electrons are counted in Helium.

My references are: 


Here where it appears that Helium has 0 valence electrons because the shells are finished
Here where it appears that Helium has two valence electrons (which is what I thought)


How many valence electrons does helium have?
Helium has two electrons in total, and according to the aufbau principle, it adopts the electronic configuration $\mathrm{1s^2}$. This means it has two electrons in s orbitals with a principal quantum number of 1. 

The last (and only) level of helium's electronic configuration is $\mathrm{1s^2}$, and therefore $\ce{He}$ has 2 valence electrons.