macro 
    /usr/local/lib/janet/spork/misc.janet  on  line  216 , column  1 
    (log  level  &  args )
    Print  to  a  dynamic  binding  stream  if  that  stream  is  set , otherwise  
    do  nothing.  Evaluate  to  nil.  For  example , `(log :err "value error: 
    %V" my-value)`  will  print  to  `(dyn :err)`  only  if  `(dyn :err)`  has  
    been  set.