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_configuration.rs
    path of file: ./repos/aws-sdk-rust/sdk/lookoutmetrics/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 information about the SNS topic to which you want to send your alerts and the IAM role that has access to that topic.</p>
#[non_exhaustive]
#[derive(::std::clone::Clone, ::std::cmp::PartialEq, ::std::fmt::Debug)]
pub struct SnsConfiguration {
    /// <p>The ARN of the IAM role that has access to the target SNS topic.</p>
    pub role_arn: ::std::string::String,
    /// <p>The ARN of the target SNS topic.</p>
    pub sns_topic_arn: ::std::string::String,
    /
    
    pub fn build(self) -> ::std::result::Result<crate::types::SnsConfiguration, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::SnsConfiguration {
            role_arn: self.role_arn.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "role_arn",
                    "role_arn was not specified but it is required when building SnsConfiguration",
                )
            })?,
            sns_topic_arn: self.sns_topic_arn.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "sns_topic_arn",
                    "sns_topic_arn was not specified but it is required when building SnsConfiguration",
                )
            })?,
            sns_format: self.sns_format,
        })
    }