code: def compose(lead, medi, tail=0):
      
      tail_remainder = None
  
      lead = JA_LEAD.index(lead) * 588
      medi = MO.index(medi) * 28
      if tail:
          try:
              tail = JA_TAIL.index(tail)
          except ValueError:
              tail_remainder = tail
              tail = 0
  
      ccode = lead + medi + tail + 0xAC00
      return [chr(ccode)] if not tail_remainder else [chr(ccode), tail_remainder]
docs: Compose hangul using given consonant and vowel
      :param lead:  lead consonant
      :param medi:  medial vowel
      :param tail: tail consonant if any
      :return: composed hangul character