function m4000(hVars)

   local inst = mc.mcGetInstance()

   -- File input/output names. Default directory is typically C:\Mach4Hobby
   local ifilename = wx.wxGetCwd() .. "\\pp-input.txt"
   local ofilename = wx.wxGetCwd() .. "\\pp-output.nc"
   --local ifilename = wx.wxGetCwd() .. "\\Profiles\\<<your profile name here>>\\Macros\\pp-input.txt"
   --local ifilename = wx.wxGetCwd() .. "\\Profiles\\<<your profile name here>>\\Macros\\pp-output.nc"

   -- Output selection:
   --  M4000 E0 -> Do not send to live gcode execution
   --  M4000 E1 -> Send to live gcode execution
   --  M4000 F0 -> Do not save output gcode
   --  M4000 F1 -> Save output gcode
   -- Tip: It is best to always specify both parameters, since MACH remembers the last used values, e.g. M4000 E0 F1, etc.
   local execute = false
   local save_output = true
   if hVars ~= nil then
      execute = (mc.mcCntlGetLocalVar(inst, hVars, mc.SV_E) ~= 0.0)
      save_output = (mc.mcCntlGetLocalVar(inst, hVars, mc.SV_F) ~= 0.0)
   end

   -- Remove comment from string, and trailing spaces
   local function remove_comment(s)
      local i = string.find(s, "%-%-")
      if(i ~= nil) then
         s = s.sub(s, 1, i - 1)
         s = s.gsub(s, "%s+$", "")
      end
      return s
   end

   -- Detect variable definition
   local function is_def(s)
      local i = string.find(s, ">>")
      return i == 1
   end

   -- Detect multiline variable definitions, replace with newline if found
   local function is_multiline_def(s)
      local i = string.find(s, ";")
      if(i ~= nil) then
         return true, s.sub(s, 1, i - 1) .. "\n"
      else
         return false, s
      end
   end

   -- Extract defined variable and its value
   local function extract_var(s)
      local i1 = string.find(s, "%s")
      if(i1 == nil) then 
         return s.sub(s, 3), ""
      end
      local var = s.sub(s, 3, i1 - 1)
      local i2 = string.find(s, "%S", i1)
      if(i2 ~= nil) then
         return var, s.sub(s, i2)
      else        
         return var, ""
      end
   end

   -- Detect variable reference
   local function is_ref(s)
      local i1 = string.find(s, "<<")
      if(i1 ~= nil) then
         local i2 = string.find(s, "%W", i1 + 2)
         if(i2 ~= nil) then
               return true, s.sub(s, i1 + 2, i2 - 1)
         else
               return true, s.sub(s, i1 + 2)
         end
      else
         return false, ""
      end
   end

   -- Replace variable references
   local function replace_ref(s, var, val)
      return string.gsub(s, "<<" .. var, val)
   end

   -- Get next non-empty line from file, remove comments
   local function get_next_line(ifile)
      while(true) do
         local line = ifile:read("*line")
         if(line ~= nil) then
               line = remove_comment(line)
               if(string.len(line) > 0) then
                  return line
               end
         else
               return nil
         end
      end
   end

   -- Open input/output files
   local ifile = io.open(ifilename, "r")
   if(ifile == nil) then
      mc.mcCntlSetLastError(inst, "Failed to open input file " .. ifilename)
      return
   end

   local ofile
   if(save_output) then
      ofile = io.open(ofilename, "w")
      if(ofile == nil) then
         mc.mcCntlSetLastError(inst, "Failed to open output file " .. ofilename)
         return
      end
   end

   local vars = {}
   while(true) do
      local ret
      local line = get_next_line(ifile)
      if(line == nil) then
         break
      end
      if(is_def(line)) then
         -- Process variable definition, possibly multiline
         ret, line = is_multiline_def(line)
         while(ret) do
               local line_cont = get_next_line(ifile)
               if(line_cont ~= nil) then
                  line = line .. line_cont
                  ret, line = is_multiline_def(line)
               else
                  break
               end
         end
         var, val = extract_var(line)
         vars[var] = val
      else
         -- Process output line, replacing variable references
         ret, var = is_ref(line)
         while(ret) do
               val = vars[var]
               if(val == nil) then
                  -- Unknown variable, output without changes
                  mc.mcCntlSetLastError(inst, "Unknown varable [" .. var .. "]")
                  break
               end
               line = replace_ref(line, var, val)
               ret, var = is_ref(line)
         end

         -- Save output/execute
         if(ofile ~= nil) then
            ofile:write(line .. "\n")
         end
         if(execute) then
            mc.mcCntlGcodeExecuteWait(inst, line)
         end
      end
   end

   io.close(ifile)
   if(ofile ~= nil) then
      io.close(ofile)
   end

end

if (mc.mcInEditor() == 1) then
	m4000()
end