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: _function_metadata.rs
    path of file: ./repos/aws-sdk-rust/sdk/cloudfront/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 metadata about a CloudFront function.</p>
#[non_exhaustive]
#[derive(::std::clone::Clone, ::std::cmp::PartialEq, ::std::fmt::Debug)]
pub struct FunctionMetadata {
    /// <p>The Amazon Resource Name (ARN) of the function. The ARN uniquely identifies the function.</p>
    pub function_arn: ::std::string::String,
    /// <p>The stage that the function is in, either <code>DEVELOPMEN
    
    pub fn build(self) -> ::std::result::Result<crate::types::FunctionMetadata, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::FunctionMetadata {
            function_arn: self.function_arn.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "function_arn",
                    "function_arn was not specified but it is required when building FunctionMetadata",
                )
            })?,
            stage: self.stage,
            created_time: self.created_time,
            last_modified_time: self.last_modified_time.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "last_modified_time",
                    "last_modified_time was not specified but it is required when building FunctionMetadata",
                )
            })?,
        })
    }