code: def is_colour(value):
      
      global PREDEFINED, HEX_MATCH, RGB_MATCH, RGBA_MATCH, HSL_MATCH, HSLA_MATCH
      value = value.strip()
  
      # hex match
      if HEX_MATCH.match(value) or RGB_MATCH.match(value) or \
              RGBA_MATCH.match(value) or HSL_MATCH.match(value) or \
              HSLA_MATCH.match(value) or value in PREDEFINED:
          return True
  
      return False
docs: Returns True if the value given is a valid CSS colour, i.e. matches one
      of the regular expressions in the module or is in the list of
      predetefined values by the browser.