Fix a typo in logic (l -> lst)

Author: alex-gl

notebooks/04_logic.ipynb

@@ -530,9 +530,9 @@
         "In this example, the function `is_divisible_by_3(x)` returns `True` or `False` when `x` is (or is not) a multiple of $3$. Here, `True` and `False` are *Boolean values*. We may want to check whether \n",
         "a list `lst` of integers contains a multiple of $3$. For that, we use a special Python construction. First, `[is_divisible_by_3(x) for x in lst]` is the list of Boolean values `is_divisible_by_3(x)` for all elements `x` in the list `lst`. \n",
         "\n",
-        "In our example, `l=[5,17,6,10]`, so this list equals `[False, False, True, False]` (only $6$ is divisible by $3$). Then, `any(S)` checks whether there exists a `True` value in `S`, and `not` reverses the answer. This way, we evaluate the statement *there is no element `x` in the list `lst` that is divisible by $3$*. \n",
+        "In our example, `lst=[5,17,6,10]`, so this list equals `[False, False, True, False]` (only $6$ is divisible by $3$). Then, `any(S)` checks whether there exists a `True` value in `S`, and `not` reverses the answer. This way, we evaluate the statement *there is no element `x` in the list `lst` that is divisible by $3$*. \n",
         "\n",
-        "In the next line, we evaluate the statement *all elements of `l` are not divisible by $3$* and get the same answer `False`: there is no good element in the list if and only if all elements are bad."
+        "In the next line, we evaluate the statement *all elements of `lst` are not divisible by $3$* and get the same answer `False`: there is no good element in the list if and only if all elements are bad."
       ]
     }
   ]