diff --git a/c2c/template/__init__.py b/c2c/template/__init__.py
index c640b3d..d3a23b0 100644
--- a/c2c/template/__init__.py
+++ b/c2c/template/__init__.py
@@ -80,7 +80,7 @@ def transform_path(
                     "The key '%s' in '%s' is not present in: [%s]",
                     key,
                     current_path,
-                    ", ".join([f"'{k}'" for k in value.keys()]),
+                    ", ".join([f"'{k}'" for k in value]),
                 )
             else:
                 if len(path) == 1:
@@ -231,7 +231,7 @@ def format_walker(
 
         elif isinstance(current_vars, dict):
             skip = []
-            for key in current_vars.keys():
+            for key in current_vars:
                 if path is None:
                     current_path = key
                     current_path_list = [key]
@@ -592,9 +592,7 @@ def __call__(self, expression: str, current_path: str) -> Value:  # type: ignore
                 try:
                     return cast(Value, eval(expression, globs))  # nosec # pylint: disable=eval-used
                 except Exception:  # pragma: nocover # pylint: disable=broad-except
-                    error = "When evaluating {} expression '{}' in '{}' as Python:\n{}".format(
-                        var_name, expression, current_path, traceback.format_exc()
-                    )
+                    error = f"When evaluating {var_name} expression '{expression}' in '{current_path}' as Python:\n{traceback.format_exc()}"
                     LOG.error(error)
                     if interpreter.get("ignore_error", False):
                         return "ERROR: " + error
@@ -626,9 +624,7 @@ def __call__(self, value: str, current_path: str) -> Value:
                 try:
                     return cast(dict[str, Any], json.loads(value))
                 except ValueError as exception:  # pragma: nocover
-                    error = "When evaluating {} expression '{}' in '{}' as JSON: {}".format(
-                        key, value, current_path, exception
-                    )
+                    error = f"When evaluating {key} expression '{value}' in '{current_path}' as JSON: {exception}"
                     LOG.error(error)
                     if interpreter.get("ignore_error", False):
                         return "ERROR: " + error
@@ -643,9 +639,7 @@ def __call__(self, value: str, current_path: str) -> Value:
                 try:
                     return cast(dict[str, Any], yaml.safe_load(value))
                 except ParserError as exception:  # pragma: nocover
-                    error = "When evaluating {} expression '{}' in '{}' as YAML: {}".format(
-                        key, value, current_path, exception
-                    )
+                    error = f"When evaluating {key} expression '{value}' in '{current_path}' as YAML: {exception}"
                     LOG.error(error)
                     if self.interpreter.get("ignore_error", False):
                         return "ERROR: " + error
@@ -684,9 +678,7 @@ def __call__(self, value: str, current_path: str) -> Value:  # type: ignore
             try:
                 return cast(Value, eval(expression, globs))  # nosec # pylint: disable=eval-used
             except ValueError as exception:  # pragma: nocover
-                error = "When interpreting the expression '{}' in '{}': {}".format(
-                    expression, current_path, exception
-                )
+                error = f"When interpreting the expression '{expression}' in '{current_path}': {exception}"
                 LOG.error(error)
                 if ignore_error:
                     return "ERROR: " + error