Read this: In parliamentary systems fashioned after the Westminster system, the prime minister is the presiding and actual head of government and head of the executive branch. In such systems, the head of state or the head of state's official representative (i.e. the monarch, president, or governor-general) usually holds a largely ceremonial position, although often with reserve powers.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What kind of role is the head of state in Westminster-based parliamentary governments?
ceremonial