This function takes in a plan of study and a course, then finds that course's deferment factor. The value captures the number of terms the student can fail the course before extending their time to degree.
deferment_factor(plan_of_study, course, expected_time_to_degree)Numeric - the deferment factor
igraph object - An igraph object created using the create_plan_of_study function
Numeric (vertex id) or String - The course to calculate the deferment factor of
Numeric - The term where students are expected to finish (often 8)