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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 proto_refactor(proto_filename, namespace, namespace_path):
 """This method refactors a Protobuf file to import from a namespace that will map to the desired python package structure. It also ensures that the syntax is set to "proto2", since protoc complains without it. Args: proto_filename (str):
 the protobuf filename to be refactored namespace (str):
 the desired package name (i.e. "dropsonde.py2") namespace_path (str):
 the desired path corresponding to the package name (i.e. "dropsonde/py2") """

    with open(proto_filename) as f:
        data = f.read()
        if not re.search('syntax = "proto2"', data):
            insert_syntax = 'syntax = "proto2";\n'
            data = insert_syntax + data
        substitution = 'import "{}/\\1";'.format(namespace_path)
        data = re.sub('import\s+"([^"]+\.proto)"\s*;', substitution, data)
        return data