prog:   ignore(<< >>)
        parse(line)\prog
        parse(error)\prog;
line:   number *;
number: ignore(none)
        sign float (exp | ={})
        = { < True: > 3 2 1 * };
sign:   <+>={} | <->={<->} | ={};
float:  int ( <.> decim = { 2 <.> 1 } | = { 1 } )
     |  <.> int = { <.> 1 };
int:    smark any(digit) string(digit) scopy;
decim:  smark string(digit) scopy;
exp:    any(<<eE>>) sign int = { <e> 2 1 };

error:  smark any(nonl) ignore(none) string(nonl) scopy * = { <False: > 1 * };

digit:  <<0123456789>>;
none:   <<>>;
nonl:   !<<
>>;