code: def copy_file_if_modified(src_path, dest_path):
      
  
      # if the destination path is a directory, delete it completely - we assume here we are
      # writing a file to the filesystem
      if os.path.isdir(dest_path):
          shutil.rmtree(dest_path)
  
      must_copy = False
      if not os.path.exists(dest_path):
          must_copy = True
      else:
          src_stat = os.stat(src_path)
          dest_stat = os.stat(dest_path)
  
          # if the size or last modified timestamp are different
          if ((src_stat[stat.ST_SIZE] != dest_stat[stat.ST_SIZE]) or
                  (src_stat[stat.ST_MTIME] != dest_stat[stat.ST_MTIME])):
              must_copy = True
  
      if must_copy:
          shutil.copy2(src_path, dest_path)
docs: Only copies the file from the source path to the destination path if it doesn't exist yet or it has
      been modified. Intended to provide something of an optimisation when a project has large trees of assets.