This screener complete the code I wrote at this link and helps to find the highs and lows as described by Williams.

Blue skies

if (high>alto[1]) and not (high<high[1] and low>low[1]) then
 alto=high
 basso=low
 markup=barindex
 markhigh=high
endif
if (low<basso[1]) and not (high<high[1] and low>low[1]) then
 alto=high
 basso=low
 markdown=barindex
 marklow=low
endif

if alto<alto[1] and trend=1 then
 trend=0
 mediummarkup=shortmarkup
 shortmarkup=markup
 longmarkhigh=mediummarkhigh
 mediummarkhigh=shortmarkhigh
 shortmarkhigh=markhigh
 //intermediate high swing points
 if longmarkhigh<mediummarkhigh and mediummarkhigh>shortmarkhigh then
  imhighold=imhighnew
  imhighnew=mediummarkhigh
  //refhigh=shortmarkup
 endif
 if imhighold>imhighnew then
  refhigh=mediummarkup
 endif
endif
if basso>basso[1] and trend=0 then
 trend=1
 mediummarkdown=shortmarkdown
 shortmarkdown=markdown
 longmarklow=mediummarklow
 mediummarklow=shortmarklow
 shortmarklow=marklow
 //intermediate low swing points
 if longmarklow>mediummarklow and mediummarklow<shortmarklow then
  imlowold=imlownew
  imlownew=mediummarklow
  //reflow=shortmarkdown
 endif
 if imlowold<imlownew then
  reflow=mediummarkdown
 endif
endif
//long conditions
c1=imlowold<imlownew and (lowest[barindex-reflow+1](low))>=mediummarklow
//short conditions
c2=imhighold>imhighnew and (highest[barindex-refhigh+1](high))<=mediummarkhigh


screener[c1 and not c2] (c1)