Call is a type of Request. Call can be used for Communicate. Communicate is a type of Convey. 
Comedy is related to Politician. Politician is related to Leader. Leader is related to Principal. 
Request <--IsA-- Call --UsedFor--> Communicate --IsA--> Convey 
Comedy <--RelatedTo--> Politician <--RelatedTo--> Leader <--RelatedTo--> Principal 