code: func IsGemInstalled(gem, version string) (bool, error) {
  	cmd, err := New("gem", "list")
  	if err != nil {
  		return false, err
  	}
  
  	out, err := cmd.RunAndReturnTrimmedCombinedOutput()
  	if err != nil {
  		return false, err
  	}
  
  	return findGemInList(out, gem, version)
  }
docs: // IsGemInstalled ...