anchor.diff:                (color r g b)))))
   
   (defmemo gray (n)
  -  "Return a gray color whose brightness is based on N."
  +  "Equivalent to (color n n n)."
     (color n n n))
   
   (defparameter white*    (gray 255)        "The color white.")
  
positive.code:   (errsafe (parse-integer str :radix 16)))
  
  (defmemo hex->color (str)
    "Convert a string represting a color to the given color."
    (and (is (len str) 6)
         (with (r (dehex (cut str 0 2))
                g (dehex (cut str 2 4))
  
negative.code: (defparameter linkblue* (color 0 0 190)   "The color of a link.")
  (defparameter orange*   (color 255 102 0) "The color orange.")
  (defparameter darkblue* (color 0 0 120)   "The color darkblue.")
  