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

    with doc.retokenize() as retokenizer:
        for ent in doc.ents:
            attrs = {"tag": ent.root.tag, "dep": ent.root.dep, "ent_type": ent.label}
            retokenizer.merge(ent, attrs=attrs)
    return doc