diff --git a/nessesary/preparer/PrepareExpression.py b/nessesary/preparer/PrepareExpression.py
new file mode 100644
index 0000000..30c2cae
--- /dev/null
+++ b/nessesary/preparer/PrepareExpression.py
@@ -0,0 +1,44 @@
+class PrepareExpression:
+    @staticmethod
+    def add_asterisks(expression):
+        result = ""
+
+        for i in range(len(expression)):
+            char = expression[i]
+            if char.isdigit() and i < len(expression) - 1 and expression[i + 1] == "(":
+                result += char + "*"
+            elif char == ")" and i < len(expression) - 1 and expression[i + 1] == "(":
+                result += char + "*"
+            else:
+                result += char
+
+        return result
+
+    @staticmethod
+    def fix_mismatched_parentheses(expression):
+        stack = []
+        result = ""
+        opening_parentheses_count = 0
+
+        for char in expression:
+            if char == "(":
+                stack.append(char)
+                opening_parentheses_count += 1
+            elif char == ")":
+                if stack:
+                    stack.pop()
+                    opening_parentheses_count -= 1
+                else:
+                    # Ignore the extra closing parenthesis
+                    continue
+            result += char
+
+        result += opening_parentheses_count * ")"
+
+        return result
+
+
+
+
+
+
diff --git a/test/preparer_tester.py b/test/preparer_tester.py
new file mode 100644
index 0000000..2da39d3
--- /dev/null
+++ b/test/preparer_tester.py
@@ -0,0 +1,52 @@
+import pytest
+import sys
+
+sys.path.append('..')
+
+from nessesary.preparer.PrepareExpression import PrepareExpression
+
+class TestPrepareExpression:
+    preparer = PrepareExpression()
+
+    def test_add_asterisks(self):
+        # Test case 1: Single level parentheses
+        expression1 = "(1+2)(3+4)"
+        result1 = self.preparer.add_asterisks(expression1)
+        assert result1 == "(1+2)*(3+4)"
+
+        # Test case 2: Nested parentheses
+        expression2 = "(1+2(2+3(3+4)))"
+        result2 = self.preparer.add_asterisks(expression2)
+        assert result2 == "(1+2*(2+3*(3+4)))"
+
+    def test_fix_mismatched_parentheses(self):
+        # Test case 1: Fixing a single mismatched closing parenthesis
+        expression1 = "(((1+2)+3)+4))"
+        fixed_expression1 = self.preparer.fix_mismatched_parentheses(expression1)
+        assert fixed_expression1 == "(((1+2)+3)+4)"
+
+        # Test case 2: Fixing a single mismatched opening parenthesis
+        expression2 = "(((1+2)+3)+4"
+        fixed_expression2 = self.preparer.fix_mismatched_parentheses(expression2)
+        assert fixed_expression2 == "(((1+2)+3)+4)"
+
+        # Test case 3: Fixing multiple mismatched parentheses
+        expression3 = "(((1+2)+3)+4))"
+        fixed_expression3 = self.preparer.fix_mismatched_parentheses(expression3)
+        assert fixed_expression3 == "(((1+2)+3)+4)"
+
+        # Test case 4: No mismatched parentheses
+        expression4 = "(((1+2)+3)+4)"
+        fixed_expression4 = self.preparer.fix_mismatched_parentheses(expression4)
+        assert fixed_expression4 == "(((1+2)+3)+4)"
+
+    def test_combined_methods(self):
+        # Test case 1: Combined methods: add_asterisks + fix_mismatched_parentheses
+        expression1 = "(((1+2)+3)+4))"
+        result1 = self.preparer.add_asterisks(expression1)
+        fixed_result1 = self.preparer.fix_mismatched_parentheses(result1)
+        assert fixed_result1 == "(((1+2)+3)+4)"
+
+
+if __name__ == "__main__":
+    pytest.main()
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