def human_indentation(indentation)
      if !indentation.include?(?\t)
        noun = 'space'
      elsif !indentation.include?(?\s)
        noun = 'tab'
      else
        return indentation.inspect
      end

      singular = indentation.length == 1
      "#{indentation.length} #{noun}#{'s' unless singular}"
    end
def human_indentation(indentation)
      if !indentation.include?(?\t)
        noun = 'space'
      elsif !indentation.include?(?\s)
        noun = 'tab'
      else
        return indentation.inspect
      end

      singular = indentation.length == 1
      "#{indentation.length} #{noun}#{'s' unless singular}"
    end
Formats a string for use in error messages about indentation.

 @param indentation [String] The string used for indentation
 @return [String] The name of the indentation (e.g. `"12 spaces"`, `"1 tab"`)