code: def set_seq1(self, a):
          
          if a is self.a:
              return
          self.a = a
          if not isinstance(self.a, list):
              self.a = list(self.a)
          # Types must be hashable to work in the c layer.  This will raise if
          # list items are *not* hashable.
          [hash(x) for x in self.a]
docs: Same as SequenceMatcher.set_seq1, but check for non-list inputs
          implementation.