[peter /tmp/bug ] $ cat module1.nim
type
  Token = ref object of RootObj
  CodeBlock = ref object of Token

method `$`(x: Token): string =
  "Bare token"

method `$`(x: CodeBlock): string =
  "Code block"
[peter /tmp/bug ] $ cat module2.nim
import module1

var x = CodeBlock()

method `$`(x: CodeBlock): string =
  result = module1.`$`(x)
  result &= "My code block"

echo x