Maintenance: fix read the docs and some annotations (#557)

src/escpos/types/__init__.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+"""Custom types."""
+
+from typing import Dict
+
+from typing_extensions import TypedDict
+
+
+class ConstTxtStyleClass(TypedDict):
+    """Describe type of :py:data:`escpos.constants.TXT_STYLES`."""
+
+    bold: Dict[bool, bytes]
+    underline: Dict[int, bytes]
+    size: Dict[str, bytes]
+    font: Dict[str, bytes]
+    align: Dict[str, bytes]
+    invert: Dict[bool, bytes]
+    color: Dict[str, bytes]
+    flip: Dict[bool, bytes]
+    density: Dict[int, bytes]
+    smooth: Dict[bool, bytes]
+    height: Dict[int, int]
+    width: Dict[int, int]