function 
    /usr/local/lib/janet/jpm/dagbuild.janet  on  line  12 , column  1 
    (pmap  f  data )
    Function  form  of  `ev/gather` .  If  any  of  the  sibling  fibers  error , 
    all  other  siblings  will  be  canceled.  Returns  the  gathered  results  
    in  an  array.