code: private static Node createAssignStatementNode(String name, Node expression) {
      // Create 'name = result-expression;' statement.
      // EXPR (ASSIGN (NAME, EXPRESSION))
      Node nameNode = IR.name(name);
      Node assign = IR.assign(nameNode, expression);
      return NodeUtil.newExpr(assign);
    }
docs: Create a valid statement Node containing an assignment to name of the
  given expression.