OptionIntro.cs

public Option<ResumeKeyword> GetKeyword(
   IDictionary<string, ResumeKeyword> keywords, 
   string word) { 

  // Ensure we're searching for a lower-cased non-null word
  string key = word ?? word.ToLowerInvariant() : string.Empty;

  // If the keyword is present, return it
  if (keywords.ContainsKey(key)) {
    return keywords[key]; // Implicitly converted to Some<ResumeKeyword>
  }

  // No keyword found
  return Option<ResumeKeyword>.None;
}