For YBC bend reports,
Y - The value is the length along the stock
before the bend.
B - The B value is the rotation angle about the Y-axis
of the stock.
C - The C value is the bend angle.
Radii - The radius of the bend.

The last bend value (y[num_bends-1],...,radii[num_bends-1])
isn't actually a bend, the only valid value is the y value, which is the
length after the last bend.
All values are relative, meaning they are calculated from the previous bend.
So if bend1 has B value of 90 degrees, and bend2 has a B value of 90 degrees
then the pipe has rotated 180 degrees about the y axis.