def set_widths file, line, method
      @format = LocationFormat.new file: file, line: line, method: method
    end
def set_widths file, line, method
      @format = LocationFormat.new file: file, line: line, method: method
    end
Creates a printf format for the given widths, for aligning output. To lead lines with zeros
 (e.g., "00317") the line argument must be a string, with leading zeros, not an integer.