documentation of fusemvo function in sensor fusion toolbox

How is the fusion of monocular visual odometry pose handled in the fusemvo function in the sensor fusion toolbox?

I have tried to search for the function script in the toolbox folder but could not actually find it.

The function is documented here : https://au.mathworks.com/help/nav/ref/errorstateimugpsfuser.fusemvo.html

However, there are no details regarding how the computations are actually performed.

Any help or pointers would be appreciated.