Merge 295fe153ad into b492a9d765

Hello, I've added a small blockquote below the description to indicate that this method of accessing an indefinite number of function arguments has been superseded by the use of the spread operator via rest parameters for ES6+ compatibility.

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1509 TILs and counting..._
+_1510 TILs and counting..._
 
 ---
 
@@ -888,6 +888,7 @@ _1509 TILs and counting..._
 - [Access Instance Variables](python/access-instance-variables.md)
 - [Create A Dummy DataFrame In Pandas](python/create-a-dummy-dataframe-in-pandas.md)
 - [Dunder Methods](python/dunder-methods.md)
+- [Override The Boolean Context Of A Class](python/override-the-boolean-context-of-a-class.md)
 - [Store And Access Immutable Data In A Tuple](python/store-and-access-immutable-data-in-a-tuple.md)
 - [Test A Function With Pytest](python/test-a-function-with-pytest.md)
 - [Use pipx To Install End User Apps](python/use-pipx-to-install-end-user-apps.md)

javascript/accessing-arguments-to-a-function.md

@@ -5,6 +5,8 @@ an array-like object with all of the arguments to the function. Even if not
 all of the arguments are referenced in the function signature, they can
 still be accessed via the `arguments` object.
 
+> For ES6+ compatibility, the `spread` operator used via [rest parameters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters) is preferred over the `arugments` object when accessing an abritrary number of function arguments.
+
 ```javascript
 function argTest(one) {
   console.log(one);

python/override-the-boolean-context-of-a-class.md

@@ -0,0 +1,86 @@
+# Override The Boolean Context Of A Class
+
+Everything in Python has a truthiness that can be checked with `bool()`. An
+empty list (`[]`) is falsy. A non-empty list (`[1,2,3]`) is truthy. Similar
+with numbers:
+
+```python
+>>> bool(0)
+False
+>>> bool(1)
+True
+```
+
+Any instance of an object is going to be truthy by default. If you want to
+control in what context an instance is considered truthy or falsy, you can
+override
+[`__bool__()`](https://docs.python.org/3/reference/datamodel.html#object.__bool__).
+If that's not implemented, but
+[`__len__()`](https://docs.python.org/3/reference/datamodel.html#object.__len__)
+is, then it will fallback to that.
+
+Let's look at a few example classes:
+
+```python
+class CartZero:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+class CartBool:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+    def __bool__(self):
+        print("__bool__() override")
+        return bool(self.items)
+
+class CartLen:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+    def __len__(self):
+        print("__len__() override")
+        return len(self.items)
+
+class CartBoolAndLen:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+    def __len__(self):
+        print("__len__() override")
+        return len(self.items)
+
+    def __bool__(self):
+        print("__bool__() override")
+        return bool(self.items)
+
+cart1 = CartZero()
+cart2 = CartBool()
+cart3 = CartLen()
+cart4 = CartBoolAndLen()
+
+print("CartZero() -> %s" %(bool(cart1)))
+print('')
+print("CartBool() -> %s" %(bool(cart2)))
+print('')
+print("CartLen() -> %s" %(bool(cart3)))
+print('')
+print("CartBoolAndLen() -> %s" %(bool(cart4)))
+```
+
+An 'empty' `Cart` be default is truthy. However, we can override some
+combination of `__bool__()` or `__len__()` to give it a boolean context that
+goes `false` when "empty".
+
+```
+CartZero() -> True
+
+__bool__() override
+CartBool() -> False
+
+__len__() override
+CartLen() -> False
+
+__bool__() override
+CartBoolAndLen() -> False
+```