code: def prefix_encode(a, b):
      """
      Compresses bytestring b as a byte representing the prefix it shares with a,
      followed by the suffix bytes.
      """
  
      i = first_diff(a, b)
      return byte(i) + b[i:]
  
file_path: whoosh/src/whoosh/util/text.py
imports: import codecs, re
  from whoosh.compat import string_type, u, byte
label_desc: Use image node_id 2 for calling a global function with example usage: prefix_encode(a, b) and returns: unknown