copy method

T copy(
  1. T build(
    1. T?,
    2. T
    ), [
  2. int deep = 0
])

从复制当前节点及其后代 复制后的节点没有parent

Implementation

T copy(T Function(T?, T) build, [int deep = 0]) {
  return _innerCopy(build, null, deep);
}