Oops, this needs to be Serializable

Author: AngledLuffa

src/edu/stanford/nlp/semgraph/semgrex/Attribute.java

@@ -1,6 +1,8 @@
 package edu.stanford.nlp.semgraph.semgrex;
 
-public class Attribute {
+import java.io.Serializable;
+
+public class Attribute implements Serializable {
   final String key;
   final Object cased;
   final Object caseless;
@@ -12,4 +14,6 @@ public class Attribute {
     this.caseless = caseless;
     this.negated = negated;
   }
+
+  private static final long serialVersionUID = 973567614155612487L;
 }