You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: update_user_role.rb
    path of file: ./repos/vglist/app/graphql/mutations/users
    
    the code of the file until where you have to start completion: # typed: true
class Mutations::Users::UpdateUserRole < Mutations::BaseMutation
  description "Update a user's role. **Only available to admins using a first-party OAuth Application.**"

  argument :user_id, ID, required: true, description: "ID of user to update the role of."

    
  def resolve(user_id:, role:)
    user = User.find(user_id)

    raise GraphQL::ExecutionError, "User already has the #{role.downcase} role." if user.role == role

    user.role = role

    raise GraphQL::ExecutionError, user.errors.full_messages.join(", ") unless user.save

    {
      user: user
    }
  end