Could not create Blob error

[robertchong02]

Hi, I am actually trying to prompt Gemini to give me some gradings on students essay, however there is an error that states 
Could not create `Blob`, expected `Blob`, `dict` or an `Image` type(`PIL.Image.Image` or `IPython.display.Image`). Got a: <class 'list'>

Hereby attached my code, 

model = genai.GenerativeModel('gemini-1.5-pro')

def get_json_Gemini(file, prompt😞

    start_time = time.time()

    messages=[

            {"role": "system", "parts": ["You are a teaching assistant."]},

            {"role": "user", "parts": [prompt]},

        ],

    response = model.generate_content(

        contents=messages,

        generation_config=genai.types.GenerationConfig(

            temperature=0.9,

            max_output_tokens=1600,

        )

    )

    end_time = time.time()

    print(f"API call for {file} took {end_time - start_time:.2f} seconds")

    # Save the response to a JSON file

    write_text_to_file(f"tmp/{file}.json", json.dumps(response))

    tokens = response['usage']['total_tokens']

    return json.loads(response['choices'][0]['message']['content']), tokens

def grade_answer(file, student_answer, marking_scheme😞

    prompt = marking_scheme.replace("<ANSWER></ANSWER>", student_answer)

    retry = 0

    while True:

        try:

            content, tokens = get_json_Gemini(file, prompt)

            break

        except Exception as e:

            if retry < 2:

                retry += 1

                print(e)

                print("Retrying:", retry)

                continue

            return 0, "Error", 0, 0, True, 0, True

    marks = content['marks']

    comments = content['comments']

    copyFromInternet = content['copyFromInternet']

    generativeAI = content['generativeAI']

    manualReview = content['manualReview']

    return marks, comments, copyFromInternet, generativeAI, manualReview, tokens, False

def grade_answers(df_answers, marking_scheme😞

    start_time = time.time()

    for index, row in df_answers.iterrows():

        file = row["FileName"]

        print(f"Grading answer {index + 1}/{len(df_answers)}: {file}")

        answer = row["Answers"]

        marks, comments, copyFromInternet, generativeAI, manualReview, tokens, error = grade_answer(file, answer, marking_scheme)

        df_answers.loc[index, "Marks"] = marks

        df_answers.loc[index, "Comments"] = comments

        df_answers.loc[index, "CopyFromInternet"] = copyFromInternet

        df_answers.loc[index, "GenerativeAI"] = generativeAI

        df_answers.loc[index, "GeminiTokens"] = tokens

        df_answers.loc[index, "ManualReview"] = manualReview

        df_answers.loc[index, "Error"] = error

    end_time = time.time()

    print(f"Grading all answers took {end_time - start_time:.2f} seconds")

    return df_answers

marking_scheme = read_text_file("marking_scheme.txt")

marking_scheme

# Assuming df_answers is read from an Excel file

df_marked = grade_answers(df_answers, marking_scheme)

df_marked.to_excel("data/marks.xlsx", index=False)

print("Grading completed and results saved to data/marks.xlsx")