backspace method

Implementation

@override
DartBlockValueTreeAlgebraicNode? backspace() {
  if (rightChild != null) {
    rightChild?.backspace();
  } else if (operator != null) {
    operator = null;
    if (parent != null) {
      return parent?.replaceChild(this, leftChild);
    } else {
      leftChild?.parent = null;

      return leftChild;
    }
  } else {
    leftChild?.backspace();
  }
  if (rightChild == null && operator == null) {
    if (leftChild == null) {
      return parent?.replaceChild(this, leftChild);
    } else {
      if (parent != null) {
        return parent?.replaceChild(this, leftChild);
      } else {
        return leftChild;
      }
    }
  } else {
    /// Return 'this' instead to not have selection change.
    return this;

    /// Previously returned 'result', which change user selection to the right child
    /// when it was previously the parent arithmetic node.
  }
}