Added method to require the presence of a token

src/main/java/fr/insarennes/nperier/minichamo/utils/TokenPeekIterator.java

@@ -60,4 +60,22 @@ public class TokenPeekIterator implements PeekIterator<Token> {
         return false;
     }
 
+    public void expect(TokenType type) {
+        if(!peekIs(type)) {
+            throw new ParsingException("Expected " + type + ", got " + peek(), peek());
+        }
+    }
+
+    public void expect(TokenType type, String where) {
+        if(!peekIs(type)) {
+            throw new ParsingException("Expected " + type + " in " + where + ", got " + peek(), peek());
+        }
+    }
+
+    public void expectJunk(TokenType type) {
+        if(!junkIf(type)) {
+            throw new ParsingException("Expected " + type + ", got " + peek(), peek());
+        }
+    }
+
 }