human
Solve the following python programming problem given the following code:
def __or__(self, other) : 
    '
        Chain two callbacks, using the | operator.
        ' 
    assert isinstance (call_both, Callback) 
    def call_both() : 
        self.fire () 
        other.fire () 
return Callback (call_both) 

    
    

    Fix the buggy line: assert isinstance (call_both, Callback)
assistant
#Here is Python program to fix the buggy line: assert isinstance (call_both, Callback)
.

assert isinstance (other, Callback)