code: func (s *SyncState) MaybeFixUpResourceInstanceAddressForCount(addr addrs.AbsResource, countEnabled bool) bool {
  	s.lock.Lock()
  	defer s.lock.Unlock()
  
  	ms := s.state.Module(addr.Module)
  	if ms == nil {
  		return false
  	}
  
  	relAddr := addr.Resource
  	rs := ms.Resource(relAddr)
  	if rs == nil {
  		return false
  	}
  	huntKey := addrs.NoKey
  	replaceKey := addrs.InstanceKey(addrs.IntKey(0))
  	if !countEnabled {
  		huntKey, replaceKey = replaceKey, huntKey
  	}
  
  	is, exists := rs.Instances[huntKey]
  	if !exists {
  		return false
  	}
  
  	if _, exists := rs.Instances[replaceKey]; exists {
  		// If the replacement key also exists then we'll do nothing and keep both.
  		return false
  	}
  
  	// If we get here then we need to "rename" from hunt to replace
  	rs.Instances[replaceKey] = is
  	delete(rs.Instances, huntKey)
  	return true
  }
docs: // MaybeFixUpResourceInstanceAddressForCount deals with the situation where a
  // resource has changed from having "count" set to not set, or vice-versa, and
  // so we need to rename the zeroth instance key to no key at all, or vice-versa.
  //
  // Set countEnabled to true if the resource has count set in its new
  // configuration, or false if it does not.
  //
  // The state is modified in-place if necessary, moving a resource instance
  // between the two addresses. The return value is true if a change was made,
  // and false otherwise.