✨: add CanArrayISub protocol

Support in-place subtraction operator for array classes

Author: nstarman

src/array_api_typing/_array.py

@@ -128,6 +128,24 @@ def __sub__(self, other: Self | int | float, /) -> Self:
         ...
 
 
+class CanArrayISub(Protocol):
+    """Protocol for array classes that support the in-place subtraction operator."""
+
+    def __isub__(self, other: Self | int | float, /) -> Self:
+        """Calculates the in-place difference for each element of an array instance with the respective element of the array other.
+
+        The result of self_i - other_i must be the same as self_i + (-other_i) and must be governed by the same floating-point rules as addition (see array.__add__()).
+
+        Args:
+            other: subtrahend array. Must be compatible with self (see Broadcasting). Should have a numeric data type.
+
+        Returns:
+            self, after performing the in-place subtraction.
+
+        """  # noqa: E501
+        ...
+
+
 class CanArrayMul(Protocol):
     """Protocol for array classes that support the multiplication operator."""
 
@@ -228,6 +246,7 @@ class Array(
     CanArrayAdd,
     CanArrayIAdd,
     CanArraySub,
+    CanArrayISub,
     CanArrayMul,
     CanArrayTrueDiv,
     CanArrayFloorDiv,