@@ -16,13 +16,13 @@ jobs:
       max-parallel: 5
       fail-fast: false
       matrix:
-        python-version: ['3.8', '3.11']
+        python-version: ['3.8', '3.12']
         slycot: ["", "conda"]
         pandas: [""]
         cvxopt: ["", "conda"]
         mplbackend: [""]
         include:
-          - python-version: '3.11'
+          - python-version: '3.12'
             slycot: conda
             pandas: conda
             cvxopt: conda
 
@@ -48,6 +48,20 @@ def __missing__(self, key):
         else:
             raise KeyError(key)
 
+    # New get function for Python 3.12+ to replicate old behavior
+    def get(self, key, defval=None):
+        # If the key exists, return it
+        if self.__contains__(key):
+            return self[key]
+
+        # If not, see if it is deprecated
+        repl = self._check_deprecation(key)
+        if self.__contains__(repl):
+            return self.get(repl, defval)
+
+        # Otherwise, call the usual dict.get() method
+        return super().get(key, defval)
+
     def _check_deprecation(self, key):
         if self.__contains__(f"deprecated.{key}"):
             repl = self[f"deprecated.{key}"]
 
@@ -409,16 +409,16 @@ def test_linear_interconnect():
         ct.StateSpace)
 
     # Interconnections with nonliner I/O systems should not be linear
-    assert ~isinstance(
+    assert not isinstance(
         ct.interconnect([nl_ctrl, ss_plant, sumblk], inputs='r', outputs='y'),
         ct.StateSpace)
-    assert ~isinstance(
+    assert not isinstance(
         ct.interconnect([nl_ctrl, tf_plant, sumblk], inputs='r', outputs='y'),
         ct.StateSpace)
-    assert ~isinstance(
+    assert not isinstance(
         ct.interconnect([ss_ctrl, nl_plant, sumblk], inputs='r', outputs='y'),
         ct.StateSpace)
-    assert ~isinstance(
+    assert not isinstance(
         ct.interconnect([tf_ctrl, nl_plant, sumblk], inputs='r', outputs='y'),
         ct.StateSpace)
 
 
@@ -1579,12 +1579,12 @@ def test_linear_interconnection():
     assert isinstance(ss_siso*ss_siso, ct.StateSpace)
     assert isinstance(tf_siso*ss_siso, ct.TransferFunction)
     assert isinstance(ss_siso*tf_siso, ct.StateSpace)
-    assert ~isinstance(ss_siso*nl_siso, ct.StateSpace)
-    assert ~isinstance(nl_siso*ss_siso, ct.StateSpace)
-    assert ~isinstance(nl_siso*nl_siso, ct.StateSpace)
-    assert ~isinstance(tf_siso*nl_siso, ct.StateSpace)
-    assert ~isinstance(nl_siso*tf_siso, ct.StateSpace)
-    assert ~isinstance(nl_siso*nl_siso, ct.StateSpace)
+    assert not isinstance(ss_siso*nl_siso, ct.StateSpace)
+    assert not isinstance(nl_siso*ss_siso, ct.StateSpace)
+    assert not isinstance(nl_siso*nl_siso, ct.StateSpace)
+    assert not isinstance(tf_siso*nl_siso, ct.StateSpace)
+    assert not isinstance(nl_siso*tf_siso, ct.StateSpace)
+    assert not isinstance(nl_siso*nl_siso, ct.StateSpace)
 
 
 def predprey(t, x, u, params={}):