```ruby
require "rbNFA/version"

module RbNFA
  class Regexp
    def initialize(string)
      
    end
  end
end
```

Add basic implementation for first test in regexp.
user
```ruby
require "rbNFA/version"

module RbNFA
  class Regexp
    def initialize(string)
      
    end
  end

  class Lexer
    def lex(regexp)
      return []
    end
  end
end
```
assistant