def gen_palette( accent_seed: nil, fewest_index: 0 )
        accent_color = accent_seed || most_possible_accent_color( fewest_index )
        if !accent_color || already_have_similar_accent_color?( accent_color )
          return nil
        else
          @accent_colors << accent_color
        end

        if accent_color
          light, dark  = most_possible_around_colors( accent_color )
          text_color   = readable_textcolor bg: accent_color, accent: main_color
          {
            primary:        accent_color,
            :'pri-light' => light,
            :'pri-dark'  => dark,
            back:           @main_color,
            text:           text_color
          }
        end
      end
def gen_palette( accent_seed: nil, fewest_index: 0 )
        accent_color = accent_seed || most_possible_accent_color( fewest_index )
        if !accent_color || already_have_similar_accent_color?( accent_color )
          return nil
        else
          @accent_colors << accent_color
        end

        if accent_color
          light, dark  = most_possible_around_colors( accent_color )
          text_color   = readable_textcolor bg: accent_color, accent: main_color
          {
            primary:        accent_color,
            :'pri-light' => light,
            :'pri-dark'  => dark,
            back:           @main_color,
            text:           text_color
          }
        end
      end
Private: 生成配色方案

 accent_seed:  指定的 primary 颜色
 fewest_index: 指定倒数第几个最少的颜色
               0 - 最少的颜色;
               1 - 倒数第二少的颜色;
               以此类推

 Returns 一种配色方案