code: def file_to_base64(filename):
      with open(filename, "rb") as file:
          data = file.read()
  
      base64_str = str(base64.b64encode(data), "utf-8")
      return "data:image/png;base64," + base64_str
  
imports: import os
  import pytest
  import base64
label_desc: Use image node_id 1 for calling a global function with example usage: file_to_base64(filename) and returns: unknown