[Wannier] info begin unit_cell_cart

[Tommaso Francese]

Dear all W. users,
i’m pretty newbie in the simulation world, and i like to understand better how the wannier90 simulation software works. 
The quite stupid question is: 
how can i properly define the <begin unit_cell_cart> flag? how can i extrapolate the unit cell vector values? 

Thanks in advance,
Tommaso Francese,
Univeristà Cà Foscari di Venezia