diff --git a/src/wireviz/DataClasses.py b/src/wireviz/DataClasses.py
index d46dcb1d..56a38589 100644
--- a/src/wireviz/DataClasses.py
+++ b/src/wireviz/DataClasses.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-from typing import Optional, List, Union
+from typing import Optional, List, Union, Tuple
 from dataclasses import dataclass, field, InitVar
 from pathlib import Path
 from wireviz.wv_helper import int2tuple, aspect_ratio
@@ -19,6 +19,8 @@
 Color = str # Two-letter color name = Literal[wv_colors._color_hex.keys()]
 Colors = str # One or more two-letter color names (Color) concatenated into one string
 ColorScheme = str # Color scheme name = Literal[wv_colors.COLOR_CODES.keys()]
+NoneOrMorePins = Union[Pin, Tuple[Pin, ...], None] # None, one, or a tuple of pins
+OneOrMoreWires = Union[Wire, Tuple[Wire, ...]] # One or a tuple of wires
 
 
 @dataclass
@@ -96,7 +98,7 @@ class Connector:
     ignore_in_bom: bool = False
     additional_components: List[AdditionalComponent] = field(default_factory=list)
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
 
         if isinstance(self.image, dict):
             self.image = Image(**self.image)
@@ -148,7 +150,7 @@ def __post_init__(self):
             if isinstance(item, dict):
                 self.additional_components[i] = AdditionalComponent(**item)
 
-    def activate_pin(self, pin):
+    def activate_pin(self, pin: Pin) -> None:
         self.visible_pins[pin] = True
 
     def get_qty_multiplier(self, qty_multiplier: Optional[ConnectorMultiplier]) -> int:
@@ -186,7 +188,7 @@ class Cable:
     ignore_in_bom: bool = False
     additional_components: List[AdditionalComponent] = field(default_factory=list)
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
 
         if isinstance(self.image, dict):
             self.image = Image(**self.image)
@@ -246,7 +248,9 @@ def __post_init__(self):
             if isinstance(item, dict):
                 self.additional_components[i] = AdditionalComponent(**item)
 
-    def connect(self, from_name, from_pin, via_pin, to_name, to_pin):
+    # The *_pin arguments accept a tuple, but it seems not in use with the current code.
+    def connect(self, from_name: Optional[Designator], from_pin: NoneOrMorePins, via_pin: OneOrMoreWires,
+                to_name: Optional[Designator], to_pin: NoneOrMorePins) -> None:
         from_pin = int2tuple(from_pin)
         via_pin = int2tuple(via_pin)
         to_pin = int2tuple(to_pin)