A non-transitory machine readable medium storing a program that manages a plurality managed forwarding elements that forward data through a network is described. The fitting includes a pivotable leg support segment, wherein the fitting has a separate spring which serves to secure the leg support segment in a storage position while not being used. Each of the PID control means outputs an operation signal so that the average temperatures or gradient temperatures may be made equal to the desired values. Means for changing positions of the neurons relative to each other based on input from the user can be provided. Staples are inserted through the tissue of the graft vessel and the target vessel by pivoting the arms of a staple holder towards the anvil.