diff --git a/src/library_analyzer/processing/api/_infer_purity.py b/src/library_analyzer/processing/api/_infer_purity.py
index 6fa600f2..eee7c65b 100644
--- a/src/library_analyzer/processing/api/_infer_purity.py
+++ b/src/library_analyzer/processing/api/_infer_purity.py
@@ -130,11 +130,12 @@ def enter_call(self, node: astroid.Call) -> None:
             pass
         elif isinstance(node.func, astroid.Name):
             if node.func.name in BUILTIN_FUNCTIONS:
-                if isinstance(node.args[0], astroid.Name):
-                    impurity_indicator = check_builtin_function(node, node.func.name, node.args[0].name, True)
+                value = node.args[0]
+                if isinstance(value, astroid.Name):
+                    impurity_indicator = check_builtin_function(node, node.func.name, value.name, True)
                     self.append_reason(impurity_indicator)
                 else:
-                    impurity_indicator = check_builtin_function(node, node.func.name, node.args[0].value)
+                    impurity_indicator = check_builtin_function(node, node.func.name, value.value)
                     self.append_reason(impurity_indicator)
 
         self.append_reason([Call(Reference(node.as_string()))])
@@ -220,10 +221,9 @@ def determine_open_mode(args: list[str]) -> OpenMode:
     if len(args) == 1:
         return OpenMode.READ
 
-    if isinstance(args[1], astroid.Const):
-        mode = args[1].value
-    else:
-        mode = args[1]
+    mode = args[1]
+    if isinstance(mode, astroid.Const):
+        mode = mode.value
 
     if mode in read_mode:
         return OpenMode.READ
diff --git a/src/library_analyzer/processing/api/model/_purity.py b/src/library_analyzer/processing/api/model/_purity.py
index e0ba7023..d01d26fc 100644
--- a/src/library_analyzer/processing/api/model/_purity.py
+++ b/src/library_analyzer/processing/api/model/_purity.py
@@ -9,9 +9,10 @@
 
 # Type of access
 class Expression(astroid.NodeNG, ABC):
-    @abstractmethod
-    def __hash__(self) -> int:
-        pass
+    # @abstractmethod
+    # def __hash__(self) -> int:
+    #    pass
+    ...
 
 
 @dataclass
@@ -20,8 +21,8 @@ class AttributeAccess(Expression):
 
     name: str
 
-    def __hash__(self) -> int:
-        return hash(self.name)
+    # def __hash__(self) -> int:
+    #    return hash(self.name)
 
 
 @dataclass
@@ -31,8 +32,8 @@ class GlobalAccess(Expression):
     name: str
     module: str = "None"
 
-    def __hash__(self) -> int:
-        return hash(self.name)
+    # def __hash__(self) -> int:
+    #    return hash(self.name)
 
 
 @dataclass
@@ -42,8 +43,8 @@ class ParameterAccess(Expression):
     name: str
     function: str
 
-    def __hash__(self) -> int:
-        return hash(self.name)
+    # def __hash__(self) -> int:
+    #    return hash(self.name)
 
 
 @dataclass
@@ -53,24 +54,24 @@ class InstanceAccess(Expression):
     receiver: Expression
     target: Expression
 
-    def __hash__(self) -> int:
-        return hash((self.receiver, self.target))
+    # def __hash__(self) -> int:
+    #   return hash((self.receiver, self.target))
 
 
 @dataclass
 class StringLiteral(Expression):
     value: str
 
-    def __hash__(self) -> int:
-        return hash(self.value)
+    # def __hash__(self) -> int:
+    #    return hash(self.value)
 
 
 @dataclass
 class Reference(Expression):
     name: str
 
-    def __hash__(self) -> int:
-        return hash(self.name)
+    # def __hash__(self) -> int:
+    #     return hash(self.name)
 
 
 class ImpurityCertainty(Enum):
@@ -83,9 +84,9 @@ class ImpurityCertainty(Enum):
 class ImpurityIndicator(ABC):
     certainty: ImpurityCertainty
 
-    @abstractmethod
-    def __hash__(self) -> int:
-        pass
+    # @abstractmethod
+    # def __hash__(self) -> int:
+    #     pass
 
     @abstractmethod
     def is_side_effect(self) -> bool:
@@ -94,8 +95,8 @@ def is_side_effect(self) -> bool:
 
 @dataclass
 class ConcreteImpurityIndicator(ImpurityIndicator):
-    def __hash__(self) -> int:
-        return hash(self.certainty)
+    # def __hash__(self) -> int:
+    #     return hash(self.certainty)
 
     def is_side_effect(self) -> bool:
         return False
@@ -106,8 +107,8 @@ class VariableRead(ImpurityIndicator):
     expression: Expression
     certainty = ImpurityCertainty.MAYBE_IMPURE
 
-    def __hash__(self) -> int:
-        return hash(self.expression)
+    # def __hash__(self) -> int:
+    #     return hash(self.expression)
 
     def is_side_effect(self) -> bool:
         return False
@@ -118,8 +119,8 @@ class VariableWrite(ImpurityIndicator):
     expression: Expression
     certainty = ImpurityCertainty.MAYBE_IMPURE
 
-    def __hash__(self) -> int:
-        return hash(self.expression)
+    # def __hash__(self) -> int:
+    #     return hash(self.expression)
 
     def is_side_effect(self) -> bool:
         return True
@@ -130,8 +131,8 @@ class FileRead(ImpurityIndicator):
     source: Expression
     certainty = ImpurityCertainty.DEFINITELY_IMPURE
 
-    def __hash__(self) -> int:
-        return hash(self.source)
+    # def __hash__(self) -> int:
+    #     return hash(self.source)
 
     def is_side_effect(self) -> bool:
         return False
@@ -142,8 +143,8 @@ class FileWrite(ImpurityIndicator):
     source: Expression
     certainty = ImpurityCertainty.DEFINITELY_IMPURE
 
-    def __hash__(self) -> int:
-        return hash(self.source)
+    # def __hash__(self) -> int:
+    #     return hash(self.source)
 
     def is_side_effect(self) -> bool:
         return True
@@ -154,8 +155,8 @@ class UnknownCallTarget(ImpurityIndicator):
     expression: Expression
     certainty = ImpurityCertainty.DEFINITELY_IMPURE
 
-    def __hash__(self) -> int:
-        return hash(self.expression)
+    # def __hash__(self) -> int:
+    #     return hash(self.expression)
 
     def is_side_effect(self) -> bool:
         return True  # TODO: improve this to make analysis more precise
@@ -166,8 +167,8 @@ class Call(ImpurityIndicator):
     expression: Expression
     certainty = ImpurityCertainty.DEFINITELY_IMPURE
 
-    def __hash__(self) -> int:
-        return hash(self.expression)
+    # def __hash__(self) -> int:
+    #     return hash(self.expression)
 
     def is_side_effect(self) -> bool:
         return True  # TODO: improve this to make analysis more precise
@@ -177,8 +178,8 @@ def is_side_effect(self) -> bool:
 class SystemInteraction(ImpurityIndicator):
     certainty = ImpurityCertainty.DEFINITELY_IMPURE
 
-    def __hash__(self) -> int:
-        return hash("SystemInteraction")
+    # def __hash__(self) -> int:
+    #     return hash("SystemInteraction")
 
     def is_side_effect(self) -> bool:
         return True
@@ -192,8 +193,8 @@ class BuiltInFunction(ImpurityIndicator):
     indicator: ImpurityIndicator  # this should be a list to handle multiple reasons
     certainty: ImpurityCertainty
 
-    def __hash__(self) -> int:
-        return hash(self.indicator)
+    # def __hash__(self) -> int:
+    #     return hash(self.indicator)
 
     def is_side_effect(self) -> bool:
         return False