code: def get_pairs(word):
      """Return set of symbol pairs in a word.
  
      word is represented as tuple of symbols (symbols being variable-length strings)
      """
      pairs = set()
      prev_char = word[0]
      for char in word[1:]:
          pairs.add((prev_char, char))
          prev_char = char
      return pairs
  
imports: from __future__ import unicode_literals, division
  import sys
  import codecs
  import io
  import argparse
  import json
  import re
  from collections import defaultdict
  from io import open
label_desc: Use image node_id 2 for calling a global function with example usage: get_pairs(word) and returns: pairs