code: func WrapRegistererWithPrefix(prefix string, reg Registerer) Registerer {
  	return &wrappingRegisterer{
  		wrappedRegisterer: reg,
  		prefix:            prefix,
  	}
  }
docs: // WrapRegistererWithPrefix returns a Registerer wrapping the provided
  // Registerer. Collectors registered with the returned Registerer will be
  // registered with the wrapped Registerer in a modified way. The modified
  // Collector adds the provided prefix to the name of all Metrics it collects.
  //
  // WrapRegistererWithPrefix is useful to have one place to prefix all metrics of
  // a sub-system. To make this work, register metrics of the sub-system with the
  // wrapping Registerer returned by WrapRegistererWithPrefix. It is rarely useful
  // to use the same prefix for all metrics exposed. In particular, do not prefix
  // metric names that are standardized across applications, as that would break
  // horizontal monitoring, for example the metrics provided by the Go collector
  // (see NewGoCollector) and the process collector (see NewProcessCollector). (In
  // fact, those metrics are already prefixed with “go_” or “process_”,
  // respectively.)