1. possibly some compiled code that can be accessed by Python (e.g., functions compiled from C or FORTRAN code)

1. a file called `__init__.py` that specifies what will be executed when we type `import package_name`

You can check the location of your `__init__.py` for NumPy in python by running the code:

```{code-block} ipython

Here `append()` is what's called a *method*, which is a function "attached to" an object---in this case, the list `x`.

* Python objects such as lists, strings, etc. all have methods that are used to manipulate the data contained in the object.

* String objects have [string methods](https://docs.python.org/3/library/stdtypes.html#string-methods), list objects have [list methods](https://docs.python.org/3/tutorial/datastructures.html#more-on-lists), etc.