def code_coverage
      return 0.0 if code_lines.size.zero?
      ran_lines.size.to_f / code_lines.size.to_f
    end
def code_coverage
      return 0.0 if code_lines.size.zero?
      ran_lines.size.to_f / code_lines.size.to_f
    end
Gives a real number between 0 and 1 indicating how many lines of code have
 been executed. It ignores all lines that can not be executed such as
 comments.

 @return [Float] lines of code executed as a fraction