tostring=tostring or function(v)
 if type(v)=='boolean' then return v and'true'or'false'
 elseif type(v)=='string' then return v
 elseif type(v)=='number' then return ''..v
 else return type(v)
 end
end

function dump(t, sep)
 local s=''
 for i=1,#t do
  s=s..tostring(t[i])..(i<#t and '\n' or '')
 end
 return s
end

coresume=coresume or coroutine.resume
cocreate=cocreate or coroutine.create
print(dump{coresume(cocreate(function() local x = nil + 1 end))})