code: def remove_binding(self, function):
          
          assert callable(function)
  
          for b in self.key_bindings:
              if b.handler == function:
                  self.key_bindings.remove(b)
                  self._clear_cache()
                  return
  
          # No key binding found for this function. Raise ValueError.
          raise ValueError('Binding not found: %r' % (function, ))
docs: Remove a key binding.
  
          This expects a function that was given to `add_binding` method as
          parameter. Raises `ValueError` when the given function was not
          registered before.