code: function simplifyDoubleUnaryMinus(node) {
    if (!Node.Type.isUnaryMinus(node)) {
      return Node.Status.noChange(node);
    }
    const unaryArg = node.args[0];
    // e.g. in - -x, -x is the unary arg, and we'd want to reduce to just x
    if (Node.Type.isUnaryMinus(unaryArg)) {
      const newNode = clone(unaryArg.args[0]);
      return Node.Status.nodeChanged(
        ChangeTypes.RESOLVE_DOUBLE_MINUS, node, newNode);
    }
    // e.g. - -4, -4 could be a constant with negative value
    else if (Node.Type.isConstant(unaryArg) && parseFloat(unaryArg.value) < 0) {
      const newNode = Node.Creator.constant(parseFloat(unaryArg.value) * -1);
      return Node.Status.nodeChanged(
        ChangeTypes.RESOLVE_DOUBLE_MINUS, node, newNode);
    }
    // e.g. -(-(5+2))
    else if (Node.Type.isParenthesis(unaryArg)) {
      const parenthesisNode = unaryArg;
      const parenthesisContent = parenthesisNode.content;
      if (Node.Type.isUnaryMinus(parenthesisContent)) {
        const newNode = Node.Creator.parenthesis(parenthesisContent.args[0]);
        return Node.Status.nodeChanged(
          ChangeTypes.RESOLVE_DOUBLE_MINUS, node, newNode);
      }
    }
    return Node.Status.noChange(node);
  }
docs: Simplifies two unary minuses in a row by removing both of them. e.g. -(- 4) --> 4