Add dummy class, docstrings, type hints; argparse

This addresses iai-group#8, but not sure it closes it, addresses all issues.
Black doesn't break up long function definitions at column 80,
can that be automated by config?

python/example_script.py

@@ -8,20 +8,19 @@
 
     Typical usage example in shell CLI:
 
-    python example_script.py -i input.txt -o output.txt -m buzzfizz.json
+    python example_script.py -i input.txt -o output.txt -m buzzfizz.json \
+                             -x happy
 
     Or simply:
 
-    python example_script.py -i input.txt -o output.txt
+    python example_script.py -i input.txt -o output.txt -x happy
 
 """
 
 import argparse
 import json
 import typing
 
-def merge_conflict_function():
-    pass
 
 def dummy_line_modification(line: str, i: int, mods: typing.Dict[str, dict]) -> str:
     """Defines the modification to be perfomed for a single input line.
@@ -47,7 +46,7 @@ def dummy_line_modification(line: str, i: int, mods: typing.Dict[str, dict]) ->
     return output_line + "\n"
 
 
-def dummy_function(input_path: str, output_path: str, mod_path: str = None):
+def dummy_function(input_path: str, output_path: str, mod_path: str = None) -> None:
     """Takes input from a file, modifies each line, and writes output
     accordingly, line by line.
 
@@ -71,35 +70,87 @@ def dummy_function(input_path: str, output_path: str, mod_path: str = None):
             f_out.write(dummy_line_modification(line, i, mods))
 
 
+class DummyThing:
+    def __init__(self, mood: str, weight: float, color: str = "green") -> None:
+        """The class docstring goes under the __init__ method.
+        
+        Args:
+            mode: What mode the class should instantiate: happy or sad.
+            weight (float): How heavy this thing is in Earth gravity. 
+            color (str): The optical color label of the imaginary object.            
+        """
+        self._mood = mood
+        self._color = color
+        self._weight = weight
+
+    def weight(self) -> float:
+        """Methods can be defined that reveal private variables.
+
+        Returns:
+            float: The value of the weight of the object. 
+        """
+        return self._weight
+
+    def act(self, command: str) -> str:
+        """The object returns a string based on the command and mode.
+
+        Args:
+            command: Tell the object whether to sing or dance.
+
+        Returns:
+            A description of the resulting behavior.
+        """
+        if command == "sing":
+            if self._mood == "happy":
+                return "This DummyThing sings 'What a Wonderful World'"
+            if self._mood == "sad":
+                return "This DummyThing sings 'Everybody Hurts'"
+        if command == "dance":
+            if self._mood == "happy":
+                return "This DummyThing bobs and weaves to the beat"
+            if self._mood == "sad":
+                return "Oh no, this DummyThing fell down."
+
+
 if __name__ == "__main__":
     # Parse required (or expected) arguments passed from command-line call.
     parser = argparse.ArgumentParser()
-    named = parser.add_argument_group("Named arguments")
-    named.add_argument(
+    parser.add_argument(
         "-i",
         "--input_path",
         dest="input_path",
         help="short explanation, input",
         default="input.txt",
         required=True,
     )
-    named.add_argument(
+    parser.add_argument(
         "-o",
         "--output_path",
         dest="output_path",
         help="short explanation, output",
         default="output.txt",
         required=True,
     )
-    named.add_argument(
+    parser.add_argument(
         "-m",
         "--modification_path",
         dest="mod_path",
         help="short explanation, modifiying file",
         default=None,
         required=False,
     )
+    parser.add_argument(
+        "-x",
+        "--mood",
+        dest="mood",
+        help="The mode argument for the DummyClass object",
+        default=None,
+        required=True,
+    )
     args = parser.parse_args()
 
     # Execute script given parsed arguments.
     dummy_function(args.input_path, args.output_path, args.mod_path)
+    my_dummything = DummyThing(args.mood, 456.9)
+    print(my_dummything.act("sing"))
+    print(my_dummything.act("dance"))