title: How to check if a dictionary of a certain key contain a value?
body: <p>So if I have a dictionary, for which each key can take more that one values (i.e <code>Dictionary &lt; string , Hashset &lt; string &gt;&gt;</code>) and now I want to check if dic [key a] contain a value for example "b" in the hashset of dic[a]? How to do that?</p>