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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def identifiers(config):
 """Show list of identifiers for this prefix. Handles both the case of local file based identifiers and also image generators. Arguments: config - configuration object in which: config.klass_name - 'gen' if a generator function config.generator_dir - directory for generator code config.image_dir - directory for images Returns: ids - a list of ids """

    ids = []
    if (config.klass_name == 'gen'):
        for generator in os.listdir(config.generator_dir):
            if (generator == '__init__.py'):
                continue
            (gid, ext) = os.path.splitext(generator)
            if (ext == '.py' and
                    os.path.isfile(os.path.join(config.generator_dir, generator))):
                ids.append(gid)
    else:
        for image_file in os.listdir(config.image_dir):
            (iid, ext) = os.path.splitext(image_file)
            if (ext in ['.jpg', '.png', '.tif'] and
                    os.path.isfile(os.path.join(config.image_dir, image_file))):
                ids.append(iid)
    return ids