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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 stage(self, fileobj, creds=None, callback=None):
 """Stages data in a Mapbox-owned S3 bucket If creds are not provided, temporary credentials will be generated using the Mapbox API. Parameters fileobj: file object or filename A Python file object opened in binary mode or a filename. creds: dict AWS credentials allowing uploads to the destination bucket. callback: func A function that takes a number of bytes processed as its sole argument. Returns ------- str The URL of the staged data """


        if not hasattr(fileobj, 'read'):
            fileobj = open(fileobj, 'rb')

        if not creds:
            res = self._get_credentials()
            creds = res.json()

        session = boto3_session(
            aws_access_key_id=creds['accessKeyId'],
            aws_secret_access_key=creds['secretAccessKey'],
            aws_session_token=creds['sessionToken'],
            region_name='us-east-1')

        s3 = session.resource('s3')
        bucket = s3.Bucket(creds['bucket'])
        key = creds['key']
        bucket.upload_fileobj(fileobj, key, Callback=callback)

        return creds['url']