code: def extract_mandarin_only(text):
      """remove other symbols except for Mandarin characters in a string"""
      return "".join([c for c in text if is_mandarin(c)])
  
imports: import argparse
  import collections
  import itertools
  import os
  import random
  import re
  import sys
label_desc: Use image node_id 5 for calling a global function with example usage: extract_mandarin_only(text) and returns: str