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: _pipeline_description.rs
    path of file: ./repos/aws-sdk-rust/sdk/datapipeline/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 pipeline metadata.</p>
#[non_exhaustive]
#[derive(::std::clone::Clone, ::std::cmp::PartialEq, ::std::fmt::Debug)]
pub struct PipelineDescription {
    /// <p>The pipeline identifier that was assigned by AWS Data Pipeline. This is a string of the form <code>df-297EG78HU43EEXAMPLE</code>.</p>
    pub pipeline_id: ::std::string::String,
    /// <p>The name of the pipeline.</p>
    pub name: ::std::string::String,
    /// <p>A list of read-only fields that contain metadata about the pipeline: @userId, @accountId, and @pipelineState.</p>
    pub fields: ::std::vec::Vec<crate::types::Field>,
    /// <p>Description of the pipeline.</p>
    pub description: ::std::option::Option<::std::string::String>,
    /// <p>A list of tags to associated with a pipeline. Tags let you control access to pipelines. For more information, see <a href="http://docs.aws.amazon.com/datapipeline/latest/DeveloperGuide/dp-control-access.html">Controlling User Access to Pipelines</a> in the <i>AWS Data Pip
    
    pub fn build(self) -> ::std::result::Result<crate::types::PipelineDescription, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::PipelineDescription {
            pipeline_id: self.pipeline_id.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "pipeline_id",
                    "pipeline_id was not specified but it is required when building PipelineDescription",
                )
            })?,
            name: self.name.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "name",
                    "name was not specified but it is required when building PipelineDescription",
                )
            })?,
            fields: self.fields.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "fields",
                    "fields was not specified but it is required when building PipelineDescription",
                )
            })?,
            description: self.description,
            tags: self.tags,
        })
    }