import re


def get_all_words(model_string):
    """ Find any groups of non-maths characters in a string.

    Parameters
    ----------
    model_string : string
            The string defining the model.

    Returns
    -------
    The groups of non-maths characters.
    """
    # https://stackoverflow.com/questions/44256638/python-regular-expression-to-find-letters-and-numbers
    regex4words = r"(?<![\"=\w])(?:[^\W]+)(?![\"=\w])"
    return re.findall(regex4words, model_string)