for line 13, and 14, you can reuse the matching android attributes by defining as:
```
<attr name="android:textColor" />
<attr name="android:textAppearance" />
```

By doing so, and omitting the format value, I'm referencing the already existing attributes.
In the view's implementation, you can refer to them via ```R.styleable.<ViewName>_android_<attribute_name>``` (i.e: ```R.styleable.NumberFieldEdit_android_textAppearance```).