put the pin constants into an enum-like class

Author: pantheraleo-7

adafruit_ads1x15/ads1x15.py

@@ -23,12 +23,8 @@
     from typing import Dict, List, Optional
 
     from busio import I2C
-    from microcontroller import Pin
 except ImportError:
-    # define Pin to avoid the error:
-    #   def read(self, pin: Pin, is_differential: bool = False) -> int:
-    #   NameError: name 'Pin' is not defined
-    Pin = None
+    pass
 
 _ADS1X15_DEFAULT_ADDRESS = const(0x48)
 _ADS1X15_POINTER_CONVERSION = const(0x00)
@@ -53,15 +49,18 @@
     16: 0x0A00,
 }
 
-# Pins
-A0 = 0
-"""Analog Pin 0"""
-A1 = 1
-"""Analog Pin 1"""
-A2 = 2
-"""Analog Pin 2"""
-A3 = 3
-"""Analog Pin 3"""
+
+class Pin:
+    """An enum-like class representing possible ADC pins."""
+
+    A0 = 0
+    """Analog Pin 0"""
+    A1 = 1
+    """Analog Pin 1"""
+    A2 = 2
+    """Analog Pin 2"""
+    A3 = 3
+    """Analog Pin 3"""
 
 
 class Mode:
@@ -137,7 +136,7 @@ class ADS1x15:
 
     def __init__(
         self,
-        i2c: I2C,
+        i2c: "I2C",
         gain: float = 1,
         data_rate: Optional[int] = None,
         mode: int = Mode.SINGLE,
@@ -330,7 +329,7 @@ def comparator_latch(self, comp_latch: int) -> None:
         if self.initialized:
             self._write_config()
 
-    def read(self, pin: Pin) -> int:
+    def read(self, pin: Optional[int]) -> int:
         """I2C Interface for ADS1x15-based ADCs reads.
 
         :param ~microcontroller.Pin pin: individual or differential pin.
@@ -350,7 +349,7 @@ def _conversion_value(self, raw_adc: int) -> int:
         """
         raise NotImplementedError("Subclass must implement _conversion_value function!")
 
-    def _read(self, pin: Pin) -> int:
+    def _read(self, pin: Optional[int]) -> int:
         """Perform an ADC read. Returns the signed integer result of the read."""
         # Immediately return conversion register result if in CONTINUOUS mode
         # and pin has not changed