code: func (i *info) GroupHas(p ...perm) bool {
  	mode := i.fi.Mode()
  
  	for _, v := range p {
  		switch v {
  		case R:
  			if mode&modeRGroup == 0 {
  				return false
  			}
  		case W:
  			if mode&modeWGroup == 0 {
  				return false
  			}
  		case X:
  			if mode&modeXGroup == 0 {
  				return false
  			}
  		}
  	}
  	return true
  }
docs: // GroupHas reports whether the group has all given permissions.