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