code: def get_source_files(source_path):
      """Given a directory, return a listing of files to upload"""
      filenames = []
      if not os.path.exists(source_path):
          print("%s does not exist!" % source_path)
          sys.exit(0)
  
      for x in os.walk(source_path):
          for name in glob(os.path.join(x[0], "*")):
              if not os.path.isdir(name):
                  filenames.append(name)
      return filenames
  
file_path: snakemake/snakemake/executors/google_lifesciences_helper.py
imports: import argparse
  from google.cloud import storage
  from glob import glob
  import sys
  import os
label_desc: Use image node_id 3 for calling a global function with example usage: get_source_files(source_path) and returns: filenames