def flatten_data(radiance):
    """Extracts radiance arrays for a whole month
    from a dictionary into a list of arrays.

    Meant for use with a single month of data.

    Parameters
    ----------
    radiance : dict
        Dictionary containing one whole month of
        radiance arrays, with days as keys and
        arrays as values.

    Returns
    -------
    array_list : list
        List of numpy arrays (or masked numpy
        arrays) containing masked radiance values.

    Example
    -------
        >>> # Get September 2019 data (all days)
        >>> radiance = radiance_sept_2019_apr_2020.get('2019').get('09')
        >>> # Flatten dictionary to list of arrays
        >>> radiance_arrays = flatten_data(radiance)
        >>> # Display type
        >>> type(radiance_arrays)
        list
        >>> Display number of days
        >>> len(radiance_arrays)
        30
    """
    # Create list of arrays from dictionary
    array_list = [radiance.get(key) for key in radiance.keys()]

    # Return list of arrays
    return array_list