(self, left, right)
return self.create_node(node_type=op.IFF, args=(left, right))
Creates an expression of the form:
            left <-> right

        Restriction: Left and Right must be of boolean type
Creates an expression of the form:
            left <-> right
Creates an expression of the form : left < - > right
def Iff(self, left, right):
        """ Creates an expression of the form:
            left <-> right

        Restriction: Left and Right must be of boolean type
        """
        return self.create_node(node_type=op.IFF, args=(left, right))
def Iff ( self , left , right ) : return self . create_node ( node_type = op . IFF , args = ( left , right ) )