diff --git a/progs/test.py b/progs/test.py
index 718885d..4ccfb1a 100644
--- a/progs/test.py
+++ b/progs/test.py
@@ -1,17 +1,3 @@
-import math
-from re import f4, r3
-
-from abs import *
-
-
-def find_first_duplicate(nums, x):
-    num_set = set()
-    no_duplicate = -1
-
-    for i in range(len(nums)):
-        if nums[i] in num_set:
-            return nums[i]
-        else:
-            num_set.add(nums[i])
-
-    return no_duplicate
+m = 1
+for i in range(10):
+    m = m + 1
diff --git a/src/ast/nodes/ArglistNode.java b/src/ast/nodes/ArglistNode.java
index 425e4c6..a0ea25b 100644
--- a/src/ast/nodes/ArglistNode.java
+++ b/src/ast/nodes/ArglistNode.java
@@ -19,7 +19,7 @@ public ArglistNode(ArrayList<Node> arguments) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         for (var arg : arguments) {
             if (arg instanceof ExprNode) {
diff --git a/src/ast/nodes/AssignmentNode.java b/src/ast/nodes/AssignmentNode.java
index 558e392..c4a44dc 100644
--- a/src/ast/nodes/AssignmentNode.java
+++ b/src/ast/nodes/AssignmentNode.java
@@ -22,7 +22,7 @@ public AssignmentNode(Node lhr, Node assign, Node rhr) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         // errors.addAll(lhr.checkSemantics(ST, _nesting));
         errors.addAll(assign.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/AtomNode.java b/src/ast/nodes/AtomNode.java
index 47a15d7..37d4d79 100644
--- a/src/ast/nodes/AtomNode.java
+++ b/src/ast/nodes/AtomNode.java
@@ -30,7 +30,7 @@ public String getId() {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        var errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         if (val != null) {
             if ((this.typeCheck() instanceof AtomType) && ST.nslookup(this.getId()) < 0) {
diff --git a/src/ast/nodes/AugassignNode.java b/src/ast/nodes/AugassignNode.java
index 7ced63e..aef60cc 100644
--- a/src/ast/nodes/AugassignNode.java
+++ b/src/ast/nodes/AugassignNode.java
@@ -21,7 +21,7 @@ public AugassignNode(TerminalNode val) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        return new ArrayList();
+        return new ArrayList<>();
     }
 
     // FIXME: use the right type
diff --git a/src/ast/nodes/BlockNode.java b/src/ast/nodes/BlockNode.java
index d9a151d..732e89b 100644
--- a/src/ast/nodes/BlockNode.java
+++ b/src/ast/nodes/BlockNode.java
@@ -16,7 +16,7 @@ public BlockNode(ArrayList<Node> childs) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         // Check semantics for each child
         for (Node child : childs) {
diff --git a/src/ast/nodes/CompForNode.java b/src/ast/nodes/CompForNode.java
index b7c6924..405a400 100644
--- a/src/ast/nodes/CompForNode.java
+++ b/src/ast/nodes/CompForNode.java
@@ -23,7 +23,7 @@ public CompForNode(Node exprlist, Node single_expr, Node comp_iter) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         errors.addAll(exprlist.checkSemantics(ST, _nesting));
         errors.addAll(single_expr.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/CompIterNode.java b/src/ast/nodes/CompIterNode.java
index 8de9f2f..1cc8a9b 100644
--- a/src/ast/nodes/CompIterNode.java
+++ b/src/ast/nodes/CompIterNode.java
@@ -19,7 +19,7 @@ public CompIterNode(Node comp_for) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         if (comp_for != null) {
             errors.addAll(comp_for.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/CompNode.java b/src/ast/nodes/CompNode.java
index 22906df..b6e0191 100644
--- a/src/ast/nodes/CompNode.java
+++ b/src/ast/nodes/CompNode.java
@@ -20,7 +20,7 @@ public CompNode(TerminalNode op) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        return new ArrayList();
+        return new ArrayList<>();
     }
 
     // TODO: it should be boolean, right?
diff --git a/src/ast/nodes/CompoundNode.java b/src/ast/nodes/CompoundNode.java
index 845f05e..2655f35 100644
--- a/src/ast/nodes/CompoundNode.java
+++ b/src/ast/nodes/CompoundNode.java
@@ -24,7 +24,7 @@ public CompoundNode(Node ifNode, Node funcDef, Node forStmt, Node whileStmt) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         if (ifNode != null) {
             errors.addAll(ifNode.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/DottedNameNode.java b/src/ast/nodes/DottedNameNode.java
index 23f14c1..2698b1c 100644
--- a/src/ast/nodes/DottedNameNode.java
+++ b/src/ast/nodes/DottedNameNode.java
@@ -20,7 +20,7 @@ public DottedNameNode(ArrayList<TerminalNode> names) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         for (int i = 0; i < names.size(); ++i) {
             ST.insert(names.get(i).toString(), this.typeCheck(), _nesting, null);
diff --git a/src/ast/nodes/ExprNode.java b/src/ast/nodes/ExprNode.java
index 873d537..693176a 100644
--- a/src/ast/nodes/ExprNode.java
+++ b/src/ast/nodes/ExprNode.java
@@ -52,7 +52,7 @@ public String getId() {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         // check if the atom is a function
         if (atom != null && !trailers.isEmpty()) {
@@ -130,19 +130,22 @@ public String toPrint(String prefix) {
         if (atom != null) {
             str += atom.toPrint(prefix);
         }
-
         if (compOp != null) {
             str += compOp.toPrint(prefix);
         }
-
-        for (var expr : exprs) {
-            str = expr.toPrint(prefix);
-        }
-
-        for (var trailer : trailers) {
-            str = trailer.toPrint(prefix);
+        
+        if (exprs != null) {
+            for (var expr : exprs) {
+                str += expr.toPrint(prefix);
+            }
         }
-
+        
+        if (trailers != null) {
+            for (var trailer : trailers) {
+                str += trailer.toPrint(prefix);
+            }
+        } 
+        
         if (op != null) {
             str += prefix + "Op(" + op + ")\n";
         }
diff --git a/src/ast/nodes/ForStmtNode.java b/src/ast/nodes/ForStmtNode.java
index 74c6ffc..50574f0 100644
--- a/src/ast/nodes/ForStmtNode.java
+++ b/src/ast/nodes/ForStmtNode.java
@@ -34,7 +34,7 @@ public ForStmtNode(Node exprList, Node block) {
      */
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         // Save every atom in the expression's list, except the last one
         var l = (ExprListNode) exprList;
diff --git a/src/ast/nodes/FuncdefNode.java b/src/ast/nodes/FuncdefNode.java
index c4f5846..91231cc 100644
--- a/src/ast/nodes/FuncdefNode.java
+++ b/src/ast/nodes/FuncdefNode.java
@@ -26,14 +26,14 @@ public FuncdefNode(TerminalNode name, Node paramlist, Node block) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
         int paramNumber = ((ParamlistNode) paramlist).getParamNumber();
         Type returnType = this.block.typeCheck();
         FunctionType ft = new FunctionType(paramNumber, returnType);
 
         ST.insert(this.name.toString(), ft, _nesting, "");
 
-        HashMap<String, STentry> HM = new HashMap();
+        HashMap<String, STentry> HM = new HashMap<>();
 
         ST.add(HM);
 
diff --git a/src/ast/nodes/IfNode.java b/src/ast/nodes/IfNode.java
index b0e1ddb..223dffb 100644
--- a/src/ast/nodes/IfNode.java
+++ b/src/ast/nodes/IfNode.java
@@ -22,7 +22,7 @@ public IfNode(Node guard, Node thenbranch, Node elsebranch) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         errors.addAll(guard.checkSemantics(ST, _nesting));
         errors.addAll(thenbranch.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/ImportNode.java b/src/ast/nodes/ImportNode.java
index 7e95ee3..f26c0d0 100644
--- a/src/ast/nodes/ImportNode.java
+++ b/src/ast/nodes/ImportNode.java
@@ -27,7 +27,7 @@ public ImportNode(Node dottedName, boolean isFrom, boolean importAs, boolean imp
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         if (isFrom) {
             for (int i = 0; i < names.size(); ++i) {
diff --git a/src/ast/nodes/ParamdefNode.java b/src/ast/nodes/ParamdefNode.java
index 6cdb2d0..e5694fa 100644
--- a/src/ast/nodes/ParamdefNode.java
+++ b/src/ast/nodes/ParamdefNode.java
@@ -17,7 +17,7 @@ public ParamdefNode(String val) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        var errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
         String paramName = this.getId();
 
         if (!ST.top_lookup(paramName)) {
diff --git a/src/ast/nodes/ParamlistNode.java b/src/ast/nodes/ParamlistNode.java
index cf75d08..e8c9a42 100644
--- a/src/ast/nodes/ParamlistNode.java
+++ b/src/ast/nodes/ParamlistNode.java
@@ -18,7 +18,7 @@ public ParamlistNode(ArrayList<Node> _params) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         for (var param : params) {
             errors.addAll(param.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/ReturnStmtNode.java b/src/ast/nodes/ReturnStmtNode.java
index 8e34813..bb49ded 100644
--- a/src/ast/nodes/ReturnStmtNode.java
+++ b/src/ast/nodes/ReturnStmtNode.java
@@ -18,7 +18,7 @@ public ReturnStmtNode(Node exprList) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         if (this.exprList != null) {
             errors.addAll(this.exprList.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/RootNode.java b/src/ast/nodes/RootNode.java
index 5bbce8c..26778f4 100644
--- a/src/ast/nodes/RootNode.java
+++ b/src/ast/nodes/RootNode.java
@@ -20,10 +20,10 @@ public RootNode(ArrayList<Node> childs) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         // Create a new HashMap for the current scope
-        HashMap<String, STentry> HM = new HashMap();
+        HashMap<String, STentry> HM = new HashMap<>();
 
         // Add the HashMap to the SymbolTable
         ST.add(HM);
diff --git a/src/ast/nodes/SimpleStmtNode.java b/src/ast/nodes/SimpleStmtNode.java
index b2bc880..fbeeb1b 100644
--- a/src/ast/nodes/SimpleStmtNode.java
+++ b/src/ast/nodes/SimpleStmtNode.java
@@ -24,7 +24,7 @@ public SimpleStmtNode(Node assignment, Node expr, Node returnStmt, Node importSt
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         if (assignment != null) {
             errors.addAll(assignment.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/SimpleStmtsNode.java b/src/ast/nodes/SimpleStmtsNode.java
index ae1044b..5377c5d 100644
--- a/src/ast/nodes/SimpleStmtsNode.java
+++ b/src/ast/nodes/SimpleStmtsNode.java
@@ -18,7 +18,7 @@ public SimpleStmtsNode(ArrayList<Node> stmts) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         for (Node stmt : stmts) {
             errors.addAll(stmt.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/TrailerNode.java b/src/ast/nodes/TrailerNode.java
index aaa72f3..d8301b8 100644
--- a/src/ast/nodes/TrailerNode.java
+++ b/src/ast/nodes/TrailerNode.java
@@ -29,7 +29,7 @@ public TrailerNode(Node arglist, ArrayList<Node> exprs, TerminalNode methodCall,
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         if (arglist != null) {
             errors.addAll(arglist.checkSemantics(ST, _nesting));
diff --git a/src/ast/nodes/WhileStmtNode.java b/src/ast/nodes/WhileStmtNode.java
index 1db01ea..352cbc0 100644
--- a/src/ast/nodes/WhileStmtNode.java
+++ b/src/ast/nodes/WhileStmtNode.java
@@ -20,7 +20,7 @@ public WhileStmtNode(Node expr, Node block) {
 
     @Override
     public ArrayList<SemanticError> checkSemantics(SymbolTable ST, int _nesting) {
-        ArrayList<SemanticError> errors = new ArrayList();
+        ArrayList<SemanticError> errors = new ArrayList<>();
 
         errors.addAll(expr.checkSemantics(ST, _nesting));
         errors.addAll(block.checkSemantics(ST, _nesting));
diff --git a/src/semanticanalysis/Share.java b/src/semanticanalysis/Share.java
index 7542cf7..a05c4c5 100644
--- a/src/semanticanalysis/Share.java
+++ b/src/semanticanalysis/Share.java
@@ -10,7 +10,7 @@ public class Share {
      * generic because it's used a custom contains function.
      */
     public static ArrayList<SemanticError> removeDuplicates(ArrayList<SemanticError> list) {
-        ArrayList<SemanticError> newList = new ArrayList();
+        ArrayList<SemanticError> newList = new ArrayList<>();
 
         for (SemanticError element : list) {
             if (!customContains(newList, element)) {
diff --git a/src/semanticanalysis/SymbolTable.java b/src/semanticanalysis/SymbolTable.java
index b620af7..50309a5 100644
--- a/src/semanticanalysis/SymbolTable.java
+++ b/src/semanticanalysis/SymbolTable.java
@@ -15,8 +15,8 @@ public class SymbolTable {
     private final ArrayList<Integer> offset;
 
     public SymbolTable() {
-        this.symbolTable = new ArrayList();
-        this.offset = new ArrayList();
+        this.symbolTable = new ArrayList<>();
+        this.offset = new ArrayList<>();
     }
 
     /**