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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 merge_noun_chunks(doc):
 """Merge noun chunks into a single token. doc (Doc):
 The Doc object. RETURNS (Doc):
 The Doc object with merged noun chunks. DOCS: https://spacy.io/api/pipeline-functions#merge_noun_chunks """

    if not doc.is_parsed:
        return doc
    with doc.retokenize() as retokenizer:
        for np in doc.noun_chunks:
            attrs = {"tag": np.root.tag, "dep": np.root.dep}
            retokenizer.merge(np, attrs=attrs)
    return doc