docs: def merge(self, other):
          """
          Merges the values
          """
          print "MERGING", self, other
          other = self.coerce(other)
          if self.is_contradictory(other):
              raise Contradiction("Cannot merge %s and %s" % (self, other))
          elif self.value is None and not other.value is None:
              self.r, self.g, self.b = other.r, other.g, other.b
              self.value = RGBColor(self.r, self.b, self.g, rgb_type='sRGB')
          # last cases:  other is none, or both are none 
          
          return self