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: _registration_type_definition.rs
    path of file: ./repos/aws-sdk-rust/sdk/pinpointsmsvoicev2/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>Provides information on the supported registration type.</p>
#[non_exhaustive]
#[derive(::std::clone::Clone, ::std::cmp::PartialEq, ::std::fmt::Debug)]
pub struct RegistrationTypeDefinition {
    /// <p>The type of registration form. The list of <b>RegistrationTypes</b> can be found using the <code>DescribeRegistrationTy
    
    pub fn build(self) -> ::std::result::Result<crate::types::RegistrationTypeDefinition, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::RegistrationTypeDefinition {
            registration_type: self.registration_type.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "registration_type",
                    "registration_type was not specified but it is required when building RegistrationTypeDefinition",
                )
            })?,
            supported_associations: self.supported_associations,
            display_hints: self.display_hints,
        })
    }