Update evaluate-sdk.md

I updated the snippet with the custom evaluator. I added the evaluator instantiation and call in 2 steps for clarity. Also removed a print statement that added nothing

Author: SeryioGonzalez

articles/ai-studio/how-to/develop/evaluate-sdk.md

@@ -368,19 +368,17 @@ Sometimes a large language model isn't needed for certain evaluation metrics. Th
 class AnswerLengthEvaluator:
     def __init__(self):
         pass
-
+    # A class is made a callable my implementing the special method __call__
     def __call__(self, *, answer: str, **kwargs):
         return {"answer_length": len(answer)}
 ```
 Then run the evaluator on a row of data by importing a callable class:
 
 ```python
-with open("answer_len/answer_length.py") as fin:
-    print(fin.read())
-
 from answer_len.answer_length import AnswerLengthEvaluator
 
-answer_length = AnswerLengthEvaluator()(answer="What is the speed of light?")
+answer_length_evaluator = AnswerLengthEvaluator()
+answer_length = answer_length_evaluator(answer="What is the speed of light?")
 
 print(answer_length)
 ```