'Checks if the query is true given the set of clauses.
Examples
>>> from sympy.logic.inference import PropKB
>>> from sympy.abc import x, y
>>> l = PropKB()
>>> l.tell(x & ~y)
>>> l.ask(x)
True
>>> l.ask(y)
False'

def ask(self, query):

    return entails(query, self.clauses_)
