def attack_vectors(color = @player_turn, proposed_manifest = @piece_locations)
      enemy_color = opposing_color(color)
      kill_zone = []

      proposed_manifest.each do |piece, details|
        kill_zone << possible_moves(piece, proposed_manifest) if details.fetch(:color) == enemy_color
      end

      kill_zone.flatten.uniq
    end
def attack_vectors(color = @player_turn, proposed_manifest = @piece_locations)
      enemy_color = opposing_color(color)
      kill_zone = []

      proposed_manifest.each do |piece, details|
        kill_zone << possible_moves(piece, proposed_manifest) if details.fetch(:color) == enemy_color
      end

      kill_zone.flatten.uniq
    end
Board spaces that are attackable by opposing pieces
  TODO: check? method should use this function