______________________________________________________________________
< In any formula, constants (especially those obtained from handbooks) >
< are to be treated as variables.                                      >
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                   \
                    \
                     \
                      $$ $$$$$ $$
                      $$ $$$$$ $$
                     .$$ $$$$$ $$.
                     :$$ $$$$$ $$:
                     $$$ $$$$$ $$$
                     $$$ $$$$$ $$$
                    ,$$$ $$$$$ $$$.
                   ,$$$$ $$$$$ $$$$.
                  ,$$$$; $$$$$ :$$$$.
                 ,$$$$$  $$$$$  $$$$$.
               ,$$$$$$'  $$$$$  `$$$$$$.
             ,$$$$$$$'   $$$$$   `$$$$$$$.
          ,s$$$$$$$'     $$$$$     `$$$$$$$s.
        $$$$$$$$$'       $$$$$       `$$$$$$$$$
        $$$$$Y'          $$$$$          `Y$$$$$