lib.util: add assert_type helper method
lib.util: add assert_type helper method

carlye566/IoT-POX,MurphyMc/pox,adusia/pox,kavitshah8/SDNDeveloper,PrincetonUniversity/pox,waltznetworks/pox,kpengboy/pox-exercise,jacobq/csci5221-viro-project,adusia/pox,PrincetonUniversity/pox,diogommartins/pox,xAKLx/pox,diogommartins/pox,kpengboy/pox-exercise,VamsikrishnaNallabothu/pox,adusia/pox,andiwundsam/_of_normalize,denovogroup/pox,denovogroup/pox,diogommartins/pox,PrincetonUniversity/pox,kpengboy/pox-exercise,diogommartins/pox,jacobq/csci5221-viro-project,VamsikrishnaNallabothu/pox,pthien92/sdn,andiwundsam/_of_normalize,carlye566/IoT-POX,pthien92/sdn,kulawczukmarcin/mypox,pthien92/sdn,diogommartins/pox,kulawczukmarcin/mypox,VamsikrishnaNallabothu/pox,jacobq/csci5221-viro-project,jacobq/csci5221-viro-project,PrincetonUniversity/pox,VamsikrishnaNallabothu/pox,pthien92/sdn,carlye566/IoT-POX,PrincetonUniversity/pox,andiwundsam/_of_normalize,waltznetworks/pox,VamsikrishnaNallabothu/pox,kavitshah8/SDNDeveloper,kulawczukmarcin/mypox,carlye566/IoT-POX,kulawczukmarcin/mypox,chenyuntc/pox,denovogroup/pox,chenyuntc/pox,kavitshah8/SDNDeveloper,noxrepo/pox,kpengboy/pox-exercise,carlye566/IoT-POX,chenyuntc/pox,adusia/pox,MurphyMc/pox,waltznetworks/pox,denovogroup/pox,pthien92/sdn,xAKLx/pox,andiwundsam/_of_normalize,noxrepo/pox,noxrepo/pox,waltznetworks/pox,xAKLx/pox,jacobq/csci5221-viro-project,MurphyMc/pox,kpengboy/pox-exercise,kavitshah8/SDNDeveloper,xAKLx/pox,xAKLx/pox,chenyuntc/pox,MurphyMc/pox,MurphyMc/pox,kulawczukmarcin/mypox,waltznetworks/pox,adusia/pox,chenyuntc/pox,noxrepo/pox,denovogroup/pox