IN PYHTON USING DEPTH FIRST TREE/GRAPH SEARCH SOLVE THE FOLLOWING PUZZEL

Three missionaries and three cannibals are on one side of a river, and they must cross a river using a boat which can carry at most two people, under the constraint that, at any time, missionaries cannot be outnumbered by cannibals (if they were, the cannibals would eat the missionaries). The boat cannot cross the river by itself with no people on board