• print is a function.
    • Parenthesis are where you place your arguments inside of them.
    • Have to start with a lowercase letter, cannot start with a number.
  • def is for definition. ``` def multiplyByThree(val): return 3 * val

multiplyByThree(4)

* keyword here is `return`
	* In the above, we are returning 3 times the value that we passed into the function.
	* Can call the function by running `multipleByThree(4)`. The output is:
`12`
* Can change this and make a function with two arguments:

def multiply(val1, val2): return val1 * val2 multiply(3, 4)

The returned value from above is `12`.
* Functions don't always have to return something.
	* Can make a function that mutates or changes a value.

a = [1,2,3]

def appendFour(myList) myList.append(4)

appendFour(a) print(a)

* Running the above function then outputs:
[1, 2, 3, 4]
* Bread going into the toaster and leaving it there for someone to collect later.
* To print the back the returned value of the print function:

print(print(‘Hello, World!’))

* This would output:

Hello, World! None ```

  • None is a special Python keyword like Null it represents the absense of value. It has its own type, called NoneType.
    • Be careful using none.
  • None + 1 does not work.

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