Sign is a type of Contract. 
you are likely to find Pill in/at/on Purse. you are likely to find Change in/at/on Purse. Change is related to Opportunity. Opportunity is related to Tune. 
Sign --IsA--> Contract 
Pill --AtLocation--> Purse <--AtLocation-- Change <--RelatedTo--> Opportunity <--RelatedTo--> Tune 