code: def visit_BinOp(self, node):
      if isinstance(node.op, gast.Add):
          node.op = gast.Sub()
      return self.generic_visit(node)
  
imports: import threading
  import gast
  from tensorflow.python.autograph.pyct import transformer
  from tensorflow.python.autograph.pyct import transpiler
  from tensorflow.python.platform import test
label_desc: Use image node_id 1 for calling the FlipSignTransformer obj's underlying member method code with example usage: obj.visit_BinOp(node) and returns: self