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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _pluralize(value, item_key):
 """"Force the value of a datacite3 key to be a list. ['Sick, Jonathan', 'Economou, Frossie'] Background When `xmltodict` proceses metadata, it turns XML tags into new key-value pairs whenever possible, even if the value should semantically be treated as a `list`. For example .. code-block:: xml <authors> <author>Sick, Jonathan</author> </authors Would be rendered by `xmltodict` as:: {'authors': {'author': 'Sick, Jonathan'}} While .. code-block:: xml <authors> <author>Sick, Jonathan</author> <author>Economou, Frossie</author> </authors is rendered by `xmltodict` as:: {'authors': [{'author': ['Sick, Jonathan', 'Economou, Frossie']}} This function ensures that values are *always* lists so that they can be treated uniformly. Parameters value : obj The value of a key from datacite metadata extracted by `xmltodict`. For example, `xmldict['authors']`. item_key : str Name of the tag for each item; for example, with the `'authors'` key the item key is `'author'`. Returns ------- item_values : list List of values of all items. """

    v = value[item_key]
    if not isinstance(v, list):
        # Force a singular value to be a list
        return [v]
    else:
        return v