code: def _get_color_definitions(data):
      
      definitions = []
      fmt = "\\definecolor{{{}}}{{rgb}}{{" + ",".join(3 * [data["float format"]]) + "}}"
      for name, rgb in data["custom colors"].items():
          definitions.append(fmt.format(name, rgb[0], rgb[1], rgb[2]))
      return definitions
docs: Returns the list of custom color definitions for the TikZ file.