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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 get_collection(source, name, collection_format, default):
 """get collection named `name` from the given `source` that formatted accordingly to `collection_format`. """

    if collection_format in COLLECTION_SEP:
        separator = COLLECTION_SEP[collection_format]
        value = source.get(name, None)
        if value is None:
            return default
        return value.split(separator)
    if collection_format == 'brackets':
        return source.getall(name + '[]', default)
    else:                       # format: multi
        return source.getall(name, default)