Custom mesh quality / edge of an mesh element

mesh
1

I would like to measure the triangular mesh quality by formula :
\frac{4 \sqrt(3) Area}{l_1^2 + l_2^2 + l_3^2}
where l_i, (i=1,2,3) is the length of an edge.
The area will be measured by
cell = Cell(mesh,index)
cell.volume().
However, for measuring lengths, I would like to extract indices of edges of a triangular element and read length of these edges. Does anybody know how to perform this in fenics? Thank you in advance.

2

Cell has a function facet_area that seems to be what you would like.