def call
      verify_oauth_signature!

      begin
        return broadcast(:ok, existing_identity.user) if existing_identity
        return broadcast(:invalid) if form.invalid?

        transaction do
          create_or_find_user
          @identity = create_identity
        end
        trigger_omniauth_registration

        broadcast(:ok, @user)
      rescue ActiveRecord::RecordInvalid => error
        broadcast(:error, error.record)
      end
    end
def call
      verify_oauth_signature!

      begin
        return broadcast(:ok, existing_identity.user) if existing_identity
        return broadcast(:invalid) if form.invalid?

        transaction do
          create_or_find_user
          @identity = create_identity
        end
        trigger_omniauth_registration

        broadcast(:ok, @user)
      rescue ActiveRecord::RecordInvalid => error
        broadcast(:error, error.record)
      end
    end
Public: Initializes the command.

 form - A form object with the params.
 Executes the command. Broadcasts these events:

 - :ok when everything is valid.
 - :invalid if the form wasn't valid and we couldn't proceed.

 Returns nothing.