code: def sep_seq(sequence, sep):
      pat = Str(sequence[0])
      for s in sequence[1:]:
          pat += sep + Str(s)
      return pat
  
imports: import os
  import re
  import sys
  from plex import Scanner, Str, Lexicon, Opt, Bol, State, AnyChar, TEXT, IGNORE
  from plex.traditional import re
label_desc: Use image node_id 1 for calling a global function with example usage: sep_seq(sequence, sep) and returns: pat