code: def mask(
      df: "SparkDataFrame",
      mask_cols: Optional[Union[str, List[str]]],
      seq_len: int,
  ):
      return callZooFunc("float", "mask", df, mask_cols, seq_len)
  
imports: from bigdl.dllib.utils.file_utils import callZooFunc
  from pyspark.sql.types import IntegerType, ShortType, LongType, FloatType, DecimalType, DoubleType, BooleanType
  from pyspark.sql.functions import broadcast, udf
  from bigdl.dllib.utils.log4Error import *
  import warnings
  from bigdl.dllib.utils.log4Error import *
  from typing import TYPE_CHECKING, Any, List, Optional, Tuple, Union
label_desc: Use image node_id 15 for calling a global function with example usage: mask(df, mask_cols, seq_len) and returns: callZooFunc