code: def _normalize(self, metric_name, submit_method, prefix):
          
          metric_prefix = "mongodb." if not prefix else "mongodb.{0}.".format(prefix)
          metric_suffix = "ps" if submit_method == RATE else ""
  
          # Replace case-sensitive metric name characters
          for pattern, repl in iteritems(self.CASE_SENSITIVE_METRIC_NAME_SUFFIXES):
              metric_name = re.compile(pattern).sub(repl, metric_name)
  
          # Normalize, and wrap
          return u"{metric_prefix}{normalized_metric_name}{metric_suffix}".format(
              normalized_metric_name=self.normalize(metric_name.lower()),
              metric_prefix=metric_prefix,
              metric_suffix=metric_suffix,
          )
docs: Replace case-sensitive metric name characters, normalize the metric name,
          prefix and suffix according to its type.