function extend(style, rule, sheet, newStyle = {}) {
  mergeExtend(style, rule, sheet, newStyle)
  mergeRest(style, rule, sheet, newStyle)
  return newStyle
}
function extend(style, rule, sheet, newStyle = {}) {
  mergeExtend(style, rule, sheet, newStyle)
  mergeRest(style, rule, sheet, newStyle)
  return newStyle
}
function extend ( style , rule , sheet , newStyle = { } ) { mergeExtend ( style , rule , sheet , newStyle ) mergeRest ( style , rule , sheet , newStyle ) return newStyle }
Recursively extend styles.
Recursively extend styles .