copy method
Implementation
void copy(IfdDirectory other) {
other.data.forEach((tag, value) => data[tag] = value.clone());
other.sub.directories
.forEach((tag, value) => sub.directories[tag] = value.clone());
}
void copy(IfdDirectory other) {
other.data.forEach((tag, value) => data[tag] = value.clone());
other.sub.directories
.forEach((tag, value) => sub.directories[tag] = value.clone());
}