code: def size_on_copy(root="."):
      
      total_size = 0
      exclusions = exclusion_policy()
      for dirpath, dirnames, filenames in os.walk(root, topdown=True):
          current_exclusions = exclusions(dirpath, os.listdir(dirpath))
          # Modifying dirnames in-place will prune the subsequent files and
          # directories visited by os.walk. This is only possible when
          # topdown = True
          dirnames[:] = [d for d in dirnames if d not in current_exclusions]
          legit_files = [f for f in filenames if f not in current_exclusions]
          for f in legit_files:
              fp = os.path.join(dirpath, f)
              total_size += os.path.getsize(fp)
      return total_size
docs: Return the size of the experiment directory in bytes, excluding any
      files and directories which would be excluded on copy.