add parameter checking
add parameter checking

johnbachman/pysb,d-fan/pysb,alubbock/pysb-legacy,LoLab-VU/pysb,alubbock/pysb-legacy,d-fan/pysb,neurord/pysb,johnbachman/pysb,jmuhlich/pysb,alubbock/pysb-legacy,alubbock/pysb,neurord/pysb,pysb/pysb,spgarbet/pysb,neurord/pysb,spgarbet/pysb,spgarbet/pysb,alubbock/pysb-legacy,d-fan/pysb,LoLab-VU/pysb