Exercise "Add an additional datasource" refers to missing load_json() function

[svenvanderburg]

The exercise "Add an additional datasource" is broken:

https://carpentries-incubator.github.io/python-intermediate-development/33-code-decoupling-abstractions/index.html#exercise-add-an-additional-datasource

It refers to a function load_json that is missing from the models.py. This is the function:

def load_json(filename):
    """Load a numpy array from a JSON document.

    Expected format:
    [
        {
            observations: [0, 1]
        },
        {
            observations: [0, 2]
        }
    ]

    :param filename: Filename of CSV to load

    """
    with open(filename, 'r', encoding='utf-8') as file:
        data_as_json = json.load(file)
        return [np.array(entry['observations']) for entry in data_as_json]

[svenvanderburg]

See suggested fix here: esciencecenter-digital-skills@7214c9b

[svenvanderburg]

Duplicate of #366 (but maybe we should keep this one, since it has a proposed solution)