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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 namespaced_view_name(view_name, metric_prefix):
 """ create string to be used as metric type """

    metric_prefix = metric_prefix or "custom.googleapis.com/opencensus"
    return os.path.join(metric_prefix, view_name).replace('\\', '/')