convenience.go
func (r *Registry) fetchCounter(name string, tags []string, factory func() interface{}) *Counter {
	v := r.Fetch(name, tags, factory)
	if i, ok := v.(*Counter); ok {
		return i
	}
	r.handleFetchError("counter", name, tags, v)
	return factory().(*Counter)
}
func (r *Registry) fetchCounter(name string, tags []string, factory func() interface{}) *Counter {
	v := r.Fetch(name, tags, factory)
	if i, ok := v.(*Counter); ok {
		return i
	}
	r.handleFetchError("counter", name, tags, v)
	return factory().(*Counter)
}
func ( r * Registry ) fetchCounter ( name string , tags [ ] string , factory func ( ) interface { } ) * Counter { v := r . Fetch ( name , tags , factory ) if i , ok := v . ( * Counter ) ; ok { return i } r . handleFetchError ( " " , name , tags , v ) return factory ( ) . ( * Counter ) }
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