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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 response_list(data, key):
 """Obtain the relevant response data in a list. If the response does not already contain the result in a list, a new one will be created to ease iteration in the parser methods. Args: data (dict):
 API response. key (str):
 Attribute of the response that contains the result values. Returns: List of response items (usually dict) or None if the key is not present. """

    if key not in data:
        return None

    if isinstance(data[key], list):
        return data[key]

    else:
        return [data[key],]