diff --git a/cctv-scheduler.py b/cctv-scheduler.py
index 722c2d2..f22d7dd 100644
--- a/cctv-scheduler.py
+++ b/cctv-scheduler.py
@@ -1524,6 +1524,37 @@ class FFmpeg:
                 return None
 
 
+class Do():
+    """Set of various methods (functions) for routine.
+    """
+    @staticmethod
+    def args_valid(arguments: dict, annotations: dict) -> bool:
+        """Arguments type validating by annotations.
+
+        Args:
+            arguments (dict): 'locals()' immediately after starting the function.
+            annotations (dict): function.name.__annotations__.
+
+        Raises:
+            TypeError: type of argument is not equal type in annotation.
+
+        Returns:
+            bool: True if argument types are valid.
+        """
+        for var_name, var_type in annotations.items():
+            if not var_name == 'return':
+                if not isinstance(arguments[var_name], var_type):
+                    raise TypeError(""
+                        + "type of '"
+                        + var_name
+                        + "' = "
+                        + str(arguments[var_name])
+                        + " is not "
+                        + str(var_type)
+                        )
+        return True
+
+
 if __name__ == "__main__":
     time_start = datetime.now()