<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def hex(self):
 """ Returns the HTML-style hex code for the Colour. Returns: str: the colour as a HTML-sytle hex string """

        return "#{:02x}{:02x}{:02x}".format(self._r, self._g, self._b).upper()