Add Document class

document.py

+class Document:
+    def __init__(self) -> None:
+        self.name = ""
+        self.title = ""
+        self.main_content = ""
+        self.attributes = {}
+
+    def __repr__(self) -> str:
+        return f"<Document {self.name!r} {self.title!r}>"
+
+    def set_name(self, name):
+        self.name = name
+
+    def set_title(self, title):
+        self.title = title
+
+    def set_main_content(self, main_content):
+        self.main_content = main_content
+
+    def set_attributes(self, attributes):
+        self.attributes = attributes
+
+    def set_attribute(self, key, value):
+        self.attributes[key] = value
+
+    def get_name(self):
+        return self.name
+
+    def get_title(self):
+        return self.title
+
+    def get_main_content(self):
+        return self.main_content
+
+    def get_attributes(self):
+        return self.attributes