merge method
Implementation
TextStyle merge(TextStyle? other) {
if (other == null) return this;
return TextStyle(
color: other.color ?? color,
backgroundColor: other.backgroundColor ?? backgroundColor,
bold: other.bold || bold,
italic: other.italic || italic,
underline: other.underline || underline,
dim: other.dim || dim,
fontFamily: other.fontFamily,
);
}