code: def generate_presigned_url(url):
      """
      Generate a presigned URL, if necessary (e.g., s3).
  
      :param url: An unsigned URL.
      :return: The presigned URL.
      """
      if url.startswith("s3"):
          client = boto3.client("s3")
  
          bucket_name, filename = (
              re.compile("s3://([\w\d\-.]+)/(.*)").search(url).groups()
          )
  
          url = client.generate_presigned_url(
              "get_object",
              Params={
                  "Bucket": bucket_name,
                  "Key": filename.replace("+", " "),
              },
          )
  
      return url
  
imports: import logging
  import os
  import re
  import shutil
  import sys
  import tempfile
  import urllib.request
  from urllib.parse import parse_qs, unquote, urlparse
  from urllib.request import urlopen
  import boto3
  import numpy
  import pkg_resources
  import scipy.io
  from google.cloud import storage
  from google.cloud.exceptions import NotFound
  from google.auth.exceptions import DefaultCredentialsError
  from ..constants.image import ALL_IMAGE_EXTENSIONS, FILE_SCHEME, PASSTHROUGH_SCHEMES, SUPPORTED_MOVIE_EXTENSIONS
  from ..constants.measurement import FTR_WELL
  from .measurement import is_well_column_token, is_well_row_token
label_desc: Use image node_id 16 for calling a global function with example usage: generate_presigned_url(url) and returns: url