old_contents: # Use x, y coords for unit positions
  # (97, 56) ... (104, 56)
  #    ...          ...
  # (97, 49) ... (104, 49)
  #
  # Algebraic notation for a position is:
  # algebraic_pos = chr(x) + chr(y)
  
new_contents: # Use x, y coords for unit positions
  # (97, 56) ... (104, 56)
  #    ...          ...
  # (97, 49) ... (104, 49)
  #
  # Algebraic notation for a position is:
  # algebraic_pos = chr(x) + chr(y)
  
  
  def _coord_to_algebraic(coord):
      x, y = coord
      return chr(x) + chr(y)
  
  
  def _algebraic_to_coord(algebraic):
      x, y = algebraic[0], algebraic[1]
      return ord(x), ord(y)
  
subject: Add _coord_to_algebraic() and _algebraic_to_coord() to convert positions between (x, y) coords and 'a1' algebraic chess notation