diff --git a/src/ytdl_sub/script/parser.py b/src/ytdl_sub/script/parser.py
index 32f4ed19..c9d10df6 100644
--- a/src/ytdl_sub/script/parser.py
+++ b/src/ytdl_sub/script/parser.py
@@ -24,6 +24,7 @@ from ytdl_sub.utils.exceptions import StringFormattingException
 from ytdl_sub.validators.string_formatter_validators import is_valid_source_variable_name
 
 # pylint: disable=invalid-name
+# pylint: disable=too-many-branches
 
 
 class ArgumentParser(Enum):
@@ -367,7 +368,8 @@ class _Parser:
 
                 self._pos += 1
                 return UnresolvedMap(value=output)
-            elif ch == ",":
+
+            if ch == ",":
                 if in_comma:
                     raise UNEXPECTED_COMMA_ARGUMENT(ArgumentParser.MAP_KEY)
                 if key is not None:
diff --git a/src/ytdl_sub/script/script.py b/src/ytdl_sub/script/script.py
index 8ae449cb..05db64b3 100644
--- a/src/ytdl_sub/script/script.py
+++ b/src/ytdl_sub/script/script.py
@@ -13,7 +13,7 @@ class Script:
         return override_name.startswith("%")
 
     @classmethod
-    def _function_name(self, function_key: str) -> str:
+    def _function_name(cls, function_key: str) -> str:
         return function_key[1:]
 
     def __init__(self, overrides: Dict[str, str]):
diff --git a/src/ytdl_sub/script/types/function.py b/src/ytdl_sub/script/types/function.py
index dce5e6ee..17f1bf09 100644
--- a/src/ytdl_sub/script/types/function.py
+++ b/src/ytdl_sub/script/types/function.py
@@ -228,7 +228,9 @@ class BuiltInFunction(Function):
                 if is_union(arg.output_type):
                     # TODO: Move naming to separate function, deal with Union input naming
                     received_type_names.append(
-                        f"%{arg.name}(...)->Union[{', '.join(arg_type.type_name() for arg_type in arg.output_type.__args__)}]"
+                        f"%{arg.name}(...)->Union["
+                        f"{', '.join(type_.type_name() for type_ in arg.output_type.__args__)}"
+                        f"]"
                     )
                 else:
                     received_type_names.append(f"%{arg.name}(...)->{arg.output_type.type_name()}")
diff --git a/src/ytdl_sub/script/types/variable_dependency.py b/src/ytdl_sub/script/types/variable_dependency.py
index 66e9f337..4bba7215 100644
--- a/src/ytdl_sub/script/types/variable_dependency.py
+++ b/src/ytdl_sub/script/types/variable_dependency.py
@@ -9,6 +9,7 @@ from ytdl_sub.script.types.resolvable import ArgumentType
 from ytdl_sub.script.types.resolvable import Resolvable
 from ytdl_sub.script.types.variable import FunctionArgument
 from ytdl_sub.script.types.variable import Variable
+from ytdl_sub.script.utils.exceptions import UNREACHABLE
 from ytdl_sub.utils.exceptions import StringFormattingException
 
 
@@ -17,12 +18,12 @@ class VariableDependency(ABC):
     @property
     @abstractmethod
     def variables(self) -> Set[Variable]:
-        raise NotImplemented()
+        raise NotImplemented
 
     @property
     @abstractmethod
     def function_arguments(self) -> Set[FunctionArgument]:
-        raise NotImplemented()
+        raise NotImplemented
 
     @abstractmethod
     def resolve(
@@ -30,10 +31,11 @@ class VariableDependency(ABC):
         resolved_variables: Dict[Variable, Resolvable],
         custom_functions: Dict[str, "VariableDependency"],
     ) -> Resolvable:
-        raise NotImplemented()
+        raise NotImplemented
 
+    @classmethod
     def _resolve_argument_type(
-        self,
+        cls,
         arg: ArgumentType,
         resolved_variables: Dict[Variable, Resolvable],
         custom_functions: Dict[str, "VariableDependency"],
@@ -49,7 +51,7 @@ class VariableDependency(ABC):
                 resolved_variables=resolved_variables, custom_functions=custom_functions
             )
 
-        assert False, "never reach here"
+        raise UNREACHABLE
 
     @final
     def has_variable_dependency(self, resolved_variables: Dict[Variable, Resolvable]) -> bool:
diff --git a/src/ytdl_sub/script/utils/parser_exception_formatter.py b/src/ytdl_sub/script/utils/parser_exception_formatter.py
index 64a326ea..c30e42bc 100644
--- a/src/ytdl_sub/script/utils/parser_exception_formatter.py
+++ b/src/ytdl_sub/script/utils/parser_exception_formatter.py
@@ -2,7 +2,6 @@ import sys
 from typing import List
 from typing import TypeVar
 
-from ytdl_sub.script.utils.exceptions import InvalidSyntaxException
 from ytdl_sub.script.utils.exceptions import UserException
 
 TUserException = TypeVar("TUserException", bound=UserException)