code: func (l *CapList) Init(cc ...Cap) {
  	if l.m == nil {
  		l.m = make(map[CapID]Cap, len(cc))
  	}
  	for _, c := range cc {
  		l.m[c.ID] = c
  	}
  }
docs: // Init initializes definition for a new capability.
  // Not safe to be called concurrently with other methods.