def _tell(self, k, v):
        if k in self and self[k] is not None:
            if self[k] == v:
                return False
            else:
                raise InconsistentAssumptions(self, k, v)
        else:
            self[k] = v
            return True

    # *********************************************
    # * This is the workhorse, so keep it *fast*. *
    # *********************************************
Add fact k=v to the knowledge base.
dataset/ETHPy150Open sympy/sympy/sympy/core/facts.py/FactKB._tell