i='A000' // rawcode of ability, which added or increased level

// for increase
if GetUnitAbilityLevel(<your unit>, i)==0x00then
 call UnitAddAbility(u, i)
else
 call IncUnitAbilityLevel(u, i)
endif

// for decrease
if GetUnitAbilityLevel==0x00then
 call UnitRemoveAbility(u, i)
else
 call DecUnitAbilityLevel(u, i)
endif

function AddSpellMod takes nothing returns nothing

local integer i
local integer index
local integer SPlvl

set i = 0
set index = 0
set SPlvl = 0
set udg_ItemID = GetItemTypeId (udg_PUitem)
set udg_key = "2crt"
call CRTmassive()

if (udg_ItemID == 1227894832) then
        loop
             exitwhen (index != 0) 
              if (udg_CRTmass[i] == 'A00I') then
                 set SPlvl = GetUnitAbilityLevel (udg_TrigUnit, 'A00I')
                 set SPlvl = SPlvl + 1
                 call SetUnitAbilityLevel (udg_TrigUnit, 'A00I', SPlvl)
                 set index = 1
                 //set udg_key = "2org"  
                 //call CRTmassive()
              endif
              if (udg_CRTmass[i] < 0) then
                 call UnitAddAbility (udg_TrigUnit, 'A00I')
                 set udg_CRTmass[i] = 'A00I'
                 set index = 1
                 set udg_key = "2org"                                                                         
                 call CRTmassive()
              endif
              set i = i + 1
              if (i == 7) then 
                 set index = 1
              endif
        endloop
   endif
endfunction

globals
   filterfunc Ftr
endglobals

//  -> create filter
function ff_gen takes nothing returns boolean
  return GetUnitTypeId(GetFilterUnit()) == 'hfoo'
endfunction

...
  set Ftr = Filter(function ff_gen)
...
//  <-

function smthn  takes nothing returns nothing
  local group g = CreateGroup()
  local player p = Player(integer)
  // -> form group
  call GroupEnumUnitsOfPlayer(g, p, ff_gen)
  // <-
 ***
  call DestroyGroup(g)
  set g = null
  set p = null
endfunction
...

call UnitRemoveAbility(u_mpu[GetPlayerId(GetTriggerPlayer())], 0x41303030)

call GroupAddGroup( GetUnitsOfPlayerAndTypeId(udg_Player, 'h000'), udg_GroupUnits )
call UnitRemoveAbilityBJ( i, GroupPickRandomUnit(udg_GroupUnits) )

u_mpu[0] = Player 1 unit
u_mpu[1] = Player 2 unit
...
u_mpu[n] = Player n+1 unit