code: def substitute_minor_for_major(progression, substitute_index,
          ignore_suffix=False):
      
      (roman, acc, suff) = parse_string(progression[substitute_index])
      res = []
  
      # Minor to major substitution
      if suff == 'm' or suff == 'm7' or suff == '' and roman in ['II', 'III', 'VI'
              ] or ignore_suffix:
          n = skip(roman, 2)
          a = interval_diff(roman, n, 3) + acc
          if suff == 'm' or ignore_suffix:
              res.append(tuple_to_string((n, a, 'M')))
          elif suff == 'm7' or ignore_suffix:
              res.append(tuple_to_string((n, a, 'M7')))
          elif suff == '' or ignore_suffix:
              res.append(tuple_to_string((n, a, '')))
      return res
docs: Substitute minor chords for its major equivalent.
  
      'm' and 'm7' suffixes recognized, and ['II', 'III', 'VI'] if there is no
      suffix.
  
      Examples:
      >>> substitute_minor_for_major(['VI'], 0)
      ['I']
      >>> substitute_minor_for_major(['Vm'], 0)
      ['bVIIM']
      >>> substitute_minor_for_major(['VIm7'], 0)
      ['IM7']