code: public int getNumberOfPredecessors() {
  
  		int numberOfPredecessors = 0;
  
  		for (int i = 0; i < this.inputGates.length; ++i) {
  			numberOfPredecessors += this.inputGates[i].getNumberOfEdges();
  		}
  
  		return numberOfPredecessors;
  	}
docs: Returns the number of predecessors, i.e. the number of vertices
  which connect to this vertex.
  
  @return the number of predecessors