Change GraphModificationFunctions to interface

src/main/java/GraphModificationFunctions.java

@@ -6,7 +6,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
-public abstract class GraphModificationFunctions {
+public interface GraphModificationFunctions {
 
     //remove over- and under-weight edges
     public static List<Integer[]> filterByOverlapThresholds(SimpleWeightedGraph<Integer, DefaultWeightedEdge> graph,

src/main/java/Simulator.java

@@ -17,7 +17,7 @@ import java.util.stream.IntStream;
 import static java.lang.Float.*;
 
 //NOTE: "sequence" in method and variable names refers to a peptide sequence from a simulated T cell
-public class Simulator {
+public class Simulator implements GraphModificationFunctions {
     private static final int cdr3AlphaIndex = 0;
     private static final int cdr3BetaIndex = 1;
     private static final int cdr1AlphaIndex = 2;