this expands a current node by defining ALL the 
        children for that process
        TODO = processes need to be recalculated

def expand(self, process, child_nodes):
        """
        this expands a current node by defining ALL the 
        children for that process
        TODO = processes need to be recalculated
        """
        #print('TODO: process check = ', process)
        #print(self.name, ' expanded to ->', child_nodes)
        self.child_nodes = []  
        for n in child_nodes:
            self.child_nodes.append(CoreData(n, parent=self))