code: func PushAttributes() {
  	p := attr{text: canvas.textColor, back: canvas.backColor}
  	canvas.attrStack = append(canvas.attrStack, p)
  }
docs: // PushAttributes saves the current back and fore colors. Useful when used with
  // PopAttributes: you can save colors then change them to anything you like and
  // as the final step just restore original colors