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: _sns_destination.rs
    path of file: ./repos/aws-sdk-rust/sdk/ses/src/types
    
    the code of the file until where you have to start completion: // Code generated by software.amazon.smithy.rust.codegen.smithy-rs. DO NOT EDIT.

/// <p>Contains the topic ARN associated with an Amazon Simple Notification Service (Amazon SNS) event destination.</p>
/// <p>Event destinations, such as Amazon SNS, are associated with configuration sets, which enable you to publish email sending events. For information about us
    
    pub fn build(self) -> ::std::result::Result<crate::types::SnsDestination, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::SnsDestination {
            topic_arn: self.topic_arn.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "topic_arn",
                    "topic_arn was not specified but it is required when building SnsDestination",
                )
            })?,
        })
    }