Fixed errors

src/main/java/ast/LiteralNode.java

@@ -1,8 +1,10 @@
 package ast;
 
 import ast.expression.ExpressionNode;
+import semantic.SemanticVisitor;
+import typechecker.TypeCheckResult;
 
-public class LiteralNode extends ExpressionNode {
+public class LiteralNode implements ExpressionNode {
 
   int value;
   private String type;
@@ -20,4 +22,8 @@ public class LiteralNode extends ExpressionNode {
   }
 
 
+  @Override
+  public TypeCheckResult accept(SemanticVisitor visitor) {
+    return null;
+  }
 }

src/main/java/ast/expression/BinaryExpressionNode.java

@@ -1,6 +1,9 @@
 package ast.expression;
 
-public class BinaryExpressionNode extends ExpressionNode {
+import semantic.SemanticVisitor;
+import typechecker.TypeCheckResult;
+
+public class BinaryExpressionNode implements ExpressionNode {
     public ExpressionNode left;
     public ExpressionNode right;
     public String operator;  // Stores the operator as a string (e.g., "+", "-", "&&")
@@ -10,4 +13,9 @@ public class BinaryExpressionNode extends ExpressionNode {
         this.right = right;
         this.operator = operator;
     }
+
+    @Override
+    public TypeCheckResult accept(SemanticVisitor visitor) {
+        return null;
+    }
 }

src/main/java/ast/expression/IdentifierExpressionNode.java

@@ -1,9 +1,18 @@
 package ast.expression;
 
-public class IdentifierExpressionNode extends ExpressionNode {
+import semantic.SemanticVisitor;
+import typechecker.TypeCheckResult;
+import typechecker.Visitable;
+
+public class IdentifierExpressionNode implements ExpressionNode {
     public String name;
 
     public IdentifierExpressionNode(String name) {
         this.name = name;
     }
+
+    @Override
+    public TypeCheckResult accept(SemanticVisitor visitor) {
+        return null;
+    }
 }

src/main/java/ast/expression/UnaryExpressionNode.java

@@ -1,6 +1,9 @@
 package ast.expression;
 
-public class UnaryExpressionNode extends ExpressionNode {
+import semantic.SemanticVisitor;
+import typechecker.TypeCheckResult;
+
+public class UnaryExpressionNode implements ExpressionNode {
     public ExpressionNode expression;
     public String operator;  // Stores the operator (e.g., "-", "!")
 
@@ -8,4 +11,9 @@ public class UnaryExpressionNode extends ExpressionNode {
         this.expression = expression;
         this.operator = operator;
     }
+
+    @Override
+    public TypeCheckResult accept(SemanticVisitor visitor) {
+        return null;
+    }
 }