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: async_graphql.rs
    path of file: ./repos/grafbase/engine/crates/operation-checks/src/schema
    
    the code of the file until where you have to start completion: use super::WrappingTypes;
use crate::schema;
use async_graphql_parser::types::ServiceDocument;
use std::collections::HashSet;

impl From<ServiceDocument> for schema::Schema {
    fn from(value: ServiceDocument) -> Self {
        let mut fields: Vec<schema::SchemaField> = Vec::new();
        let 
    
pub(crate) fn extract_type(top_level_ty: &async_graphql_parser::types::Type) -> (String, WrappingTypes) {
    let mut ty = top_level_ty;
    let mut wrapper_types = WrappingTypes::default();

    loop {
        match &ty.base {
            async_graphql_parser::types::BaseType::Named(name) => {
                wrapper_types.set_inner_nonnull(!ty.nullable);
                return (name.to_string(), wrapper_types);
            }
            async_graphql_parser::types::BaseType::List(inner) => {
                wrapper_types.push_list(!ty.nullable);
                ty = inner.as_ref();
            }
        }
    }
}