Rails 3.2.5 in `eval': wrong number of arguments (0 for 2..3) (ArgumentError)

I wrote a runner (saved in lib folder). When starting the runner with: rails runner lib/test.rb

 def aaa
     puts "aaa"
 end

 aaa

it dumps: in `eval': wrong number of arguments (0 for 2..3) (ArgumentError)

why?