docstr: Write the color palettes to a yaml file
code: def _to_yaml(self, filename):
      """Write the color palettes to a yaml file"""
      palette_list = []
      for palette in self._palettes.values():
          hex_color_list = [
              color.get_hex_l() for color in palette.colors
          ]
          palette_list.append(
              [hex_color_list, palette.palette_type, palette.name]
          )
  
      with open(filename, "w") as outfile:
          yaml.dump(palette_list, outfile, default_flow_style=False)
  
imports: from collections import OrderedDict
  from bokeh import palettes
  from IPython.core.display import HTML
  import yaml
  from chartify._core.options import options
  from chartify._core import colour
label_desc: Use image node_id 6 for calling the ColorPalettes obj's underlying member method code with example usage: obj._to_yaml(filename) without return types