An arrangement for mixing a first and a second gas flow, for example, an inlet flow with an exhaust gas return flow in a diesel engine. The first circuit board includes a first holding portion for holding the first dust proofing member. Two or more carts can be nested together by pushing the front wall of the basket of a first cart through the rear frame beneath the fixed child seat of a second cart, simultaneously pivoting the rear gate upwardly to allow the basket of the first cart to enter the basket of the second cart. Each API definition file defines items in its associated program unit that are made accessible to one or more other program units, and each implementation includes executable code corresponding to the API definition file. The \u0394VBE loop can be the portion of the circuit involved in generating the \u0394VBE voltage.