my setKMVar("MY_KM_Variable", "some new value")

on setKMVar(pKMVarNameStr, pValueStr)
  
  --- Compatible with Keyboard Maestro 6+ ---
  --     • Creates the KM Variable if does not exist (just like KM 7 setvariable)
  --     • Returns true if new Variable was created
  
  set varCreatedBool to false
  
  tell application "Keyboard Maestro Engine"
    try
      set value of variable pKMVarNameStr to pValueStr
      
    on error errMsg number errNum
      if (errNum = -10006) then --- KM Variable Does NOT Exist ---
        
        --- Create & Set KM Variable ---
        make new variable with properties {name:pKMVarNameStr, value:pValueStr}
        set varCreatedBool to true
        
      else
        error ("Error " & errNum & ":  " & errMsg)
      end if
      -- END on error
      
    end try
  end tell
  
  return varCreatedBool
  
end setKMVar