diff --git a/s23/Gurmail_lecture_notes/03_Operators/.ipynb_checkpoints/lec_03_Operators-checkpoint.ipynb b/s23/Gurmail_lecture_notes/03_Operators/.ipynb_checkpoints/lec_03_Operators-checkpoint.ipynb
index 437dcf2521a63e22404f504a4bfcd20ba44f8d77..9757c40aad1b59a66edeb047bb6c9e88768cee99 100644
--- a/s23/Gurmail_lecture_notes/03_Operators/.ipynb_checkpoints/lec_03_Operators-checkpoint.ipynb
+++ b/s23/Gurmail_lecture_notes/03_Operators/.ipynb_checkpoints/lec_03_Operators-checkpoint.ipynb
@@ -1120,7 +1120,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,
diff --git a/s23/Gurmail_lecture_notes/03_Operators/lec_03_Operators.ipynb b/s23/Gurmail_lecture_notes/03_Operators/lec_03_Operators.ipynb
index 437dcf2521a63e22404f504a4bfcd20ba44f8d77..9757c40aad1b59a66edeb047bb6c9e88768cee99 100644
--- a/s23/Gurmail_lecture_notes/03_Operators/lec_03_Operators.ipynb
+++ b/s23/Gurmail_lecture_notes/03_Operators/lec_03_Operators.ipynb
@@ -1120,7 +1120,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,
diff --git a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs-checkpoint.ipynb b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs-checkpoint.ipynb
index e4dab02aa86392c930b055417974382ac7421303..24e8d6e81724e7231fbaba53ba5d7dbfbe5b0b26 100644
--- a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs-checkpoint.ipynb
+++ b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs-checkpoint.ipynb
@@ -19,7 +19,8 @@
     "* shift + enter = cell execution (= Run)\n",
     "* ESC + A = add a cell above the current cell\n",
     "* ESC + B = add a cell below the current cell\n",
-    "* ESc + L = toggle the line numbers"
+    "* ESC + L = toggle the line numbers\n",
+    "* ctrl + / = toggle comment(s) (that is, adds/removes #)"
    ]
   },
   {
@@ -929,7 +930,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,
diff --git a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec1-checkpoint.ipynb b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec1-checkpoint.ipynb
index ce7668bfb4872bd6164998cc368bb8fe082654ba..f6f8ee1169ea884a4e888e9f8c9f31f835d3ce35 100644
--- a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec1-checkpoint.ipynb
+++ b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec1-checkpoint.ipynb
@@ -19,7 +19,8 @@
     "* shift + enter = cell execution (= Run)\n",
     "* ESC + A = add a cell above the current cell\n",
     "* ESC + B = add a cell below the current cell\n",
-    "* ESc + L = toggle the line numbers"
+    "* ESC + L = toggle the line numbers\n",
+    "* ctrl + / = toggle comment(s) (that is, adds/removes #)"
    ]
   },
   {
@@ -637,7 +638,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,
diff --git a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec2-checkpoint.ipynb b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec2-checkpoint.ipynb
index ce7668bfb4872bd6164998cc368bb8fe082654ba..f6f8ee1169ea884a4e888e9f8c9f31f835d3ce35 100644
--- a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec2-checkpoint.ipynb
+++ b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/.ipynb_checkpoints/lec_04_Vars_and_Exprs_template_Gurmail_lec2-checkpoint.ipynb
@@ -19,7 +19,8 @@
     "* shift + enter = cell execution (= Run)\n",
     "* ESC + A = add a cell above the current cell\n",
     "* ESC + B = add a cell below the current cell\n",
-    "* ESc + L = toggle the line numbers"
+    "* ESC + L = toggle the line numbers\n",
+    "* ctrl + / = toggle comment(s) (that is, adds/removes #)"
    ]
   },
   {
@@ -637,7 +638,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,
diff --git a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs.ipynb b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs.ipynb
index e4dab02aa86392c930b055417974382ac7421303..24e8d6e81724e7231fbaba53ba5d7dbfbe5b0b26 100644
--- a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs.ipynb
+++ b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs.ipynb
@@ -19,7 +19,8 @@
     "* shift + enter = cell execution (= Run)\n",
     "* ESC + A = add a cell above the current cell\n",
     "* ESC + B = add a cell below the current cell\n",
-    "* ESc + L = toggle the line numbers"
+    "* ESC + L = toggle the line numbers\n",
+    "* ctrl + / = toggle comment(s) (that is, adds/removes #)"
    ]
   },
   {
@@ -929,7 +930,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,
diff --git a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec1.ipynb b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec1.ipynb
index ce7668bfb4872bd6164998cc368bb8fe082654ba..f6f8ee1169ea884a4e888e9f8c9f31f835d3ce35 100644
--- a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec1.ipynb
+++ b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec1.ipynb
@@ -19,7 +19,8 @@
     "* shift + enter = cell execution (= Run)\n",
     "* ESC + A = add a cell above the current cell\n",
     "* ESC + B = add a cell below the current cell\n",
-    "* ESc + L = toggle the line numbers"
+    "* ESC + L = toggle the line numbers\n",
+    "* ctrl + / = toggle comment(s) (that is, adds/removes #)"
    ]
   },
   {
@@ -637,7 +638,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,
diff --git a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec2.ipynb b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec2.ipynb
index ce7668bfb4872bd6164998cc368bb8fe082654ba..f6f8ee1169ea884a4e888e9f8c9f31f835d3ce35 100644
--- a/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec2.ipynb
+++ b/s23/Gurmail_lecture_notes/04_Vars_and_Exprs/lec_04_Vars_and_Exprs_template_Gurmail_lec2.ipynb
@@ -19,7 +19,8 @@
     "* shift + enter = cell execution (= Run)\n",
     "* ESC + A = add a cell above the current cell\n",
     "* ESC + B = add a cell below the current cell\n",
-    "* ESc + L = toggle the line numbers"
+    "* ESC + L = toggle the line numbers\n",
+    "* ctrl + / = toggle comment(s) (that is, adds/removes #)"
    ]
   },
   {
@@ -637,7 +638,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.9.12"
   }
  },
  "nbformat": 4,