code: def test_str_methods():
      s = Stream.source(
          ["hello", "my", "name", "i", "am", "the", "data", "feed"],
          dtype="string",
      )
  
      w1 = s.upper().rename("w1")
      w2 = s.lower().rename("w2")
      w3 = w1.endswith("E").rename("w3")
  
      feed = DataFeed([w1, w2, w3])
      feed.compile()
  
      assert feed.next() == {"w1": "HELLO", "w2": "hello", "w3": False}
  
imports: from tensortrade.feed import DataFeed, Stream
label_desc: Use image node_id 3 for calling a global function with example usage: test_str_methods() without return types