class_docstr: Emotion Task 
docstr: convert text to id
docstr_tok: ["convert","text","to","id"]
code: def _word_table_lookup(self, text):
      """convert text to id"""
      max_text_len = self._max_text_len
      text2id = np.zeros(shape=[max_text_len])
      text = _process_text(text)
      pad_len = min(max_text_len, len(text))
      for char_num in range(pad_len):
          ## handle unk
          if text[char_num] in self.word2id:
              text2id[char_num] = self.word2id[text[char_num]]
          else:
              text2id[char_num] = self.word2id["<unk>"]
      return text2id
  
imports: import re
  import ast
  import os
  import copy
  import threading
  import itertools
  import functools
  import random
  from collections import defaultdict
  import librosa
  import numpy
  import pandas
  import delta.compat
  from absl import logging
  from sklearn.model_selection import train_test_split
  from delta import utils
  from delta.data import feat
  from delta.utils.register import registers
  from delta.data.task.base_speech_task import SpeechTask
label_desc: Use image node_id 25 for calling the SpeechClsTask obj's underlying member method code with example usage: obj._word_table_lookup(text) and returns: text2id