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: from_type_param.rs
    path of file: ./repos/darling/core/src/codegen
    
    the code of the file until where you have to start completion: use proc_macro2::TokenStream;
use quote::{quote, ToTokens};
use syn::Ident;

use crate::codegen::{ExtractAttribute, ForwardAttrs, OuterFromImpl, TraitImpl};
use crate::util::PathList;

pub struct FromTypeParamImpl<'a> {
    pub base: TraitImpl<'a>,
    pub ident: Option<&'a Ident>,
    pub bounds: Option<&'a Ident>,
    pub default: Option<&'a Ident>,
    pub attr_names: &'a PathList,
    pub forward_attrs: ForwardAttrs<'a>,
    pub from_ident: bool,
}

impl<'a> ToTokens for FromTypeParamImpl<'a> {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        let input = self.param_name();

        let error_declaration = self.base.declare_errors();
        let grab_attrs = self.extractor();
        let require_fields = self.base.require_fields();
        let error_check = self.base.check_errors();

        let default = if self.from_ident {
            quote!(let __default: Self = ::darling::export::From::from(#input.ident.clone());)
        } else {
            self.base.fallback_decl()
        };

        let passed_ident = self
            .ident
            .as_ref()
            .map(|i| quote!(#i: #input.ident.clone(),));
        let passed_attrs = self.forward_attrs.as_initializer();
        let passed_bounds = self
            .bounds
            .as_ref()
            .map(|i| quote!(#i: #input.bounds.clone().into_iter().collect::<Vec<_>>(),));
        let passed_default = self
            .default
            .as_ref()
            .map(|i| quote!(#i: #input.default.clone(),));
        let initializers = self.base.initializers();

       
    
    fn to_tokens(&self, tokens: &mut TokenStream) {
        let input = self.param_name();

        let error_declaration = self.base.declare_errors();
        let grab_attrs = self.extractor();
        let require_fields = self.base.require_fields();
        let error_check = self.base.check_errors();

        let default = if self.from_ident {
            quote!(let __default: Self = ::darling::export::From::from(#input.ident.clone());)
        } else {
            self.base.fallback_decl()
        };

        let passed_ident = self
            .ident
            .as_ref()
            .map(|i| quote!(#i: #input.ident.clone(),));
        let passed_attrs = self.forward_attrs.as_initializer();
        let passed_bounds = self
            .bounds
            .as_ref()
            .map(|i| quote!(#i: #input.bounds.clone().into_iter().collect::<Vec<_>>(),));
        let passed_default = self
            .default
            .as_ref()
            .map(|i| quote!(#i: #input.default.clone(),));
        let initializers = self.base.initializers();

        let post_transform = self.base.post_transform_call();

        self.wrap(
            quote! {
                fn from_type_param(#input: &::darling::export::syn::TypeParam) -> ::darling::Result<Self> {
                    #error_declaration

                    #grab_attrs

                    #require_fields

                    #error_check

                    #default

                    ::darling::export::Ok(Self {
                        #passed_ident
                        #passed_bounds
                        #passed_default
                        #passed_attrs
                        #initializers
                    }) #post_transform
                }
            },
            tokens,
        );
    }