def is_file?(string)
      return false if string.is_a?(StringIO)
      !File.directory?(string) && File.exists?(File.expand_path(string))
    rescue
      false
    end
def is_file?(string)
      return false if string.is_a?(StringIO)
      !File.directory?(string) && File.exists?(File.expand_path(string))
    rescue
      false
    end
Private: Check if the string is in the filesystem

 string - The string to be checked

 Returns true/false