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: namespacing.rs
    path of file: ./repos/grafbase/engine/crates/parser-openapi/src/output
    
    the code of the file until where you have to start completion: //! Module that deals with namespacing our output within the destination
//! GraphQL schema

use std::collections::BTreeMap;

use engine::{
    indexmap::IndexMap,
    registry::{MetaField, MetaType, Registry},
};
use inflector::Inflector;
    
    fn query_fields_mut(&mut self, api_metadata: &ApiMetadata) -> &mut IndexMap<String, MetaField> {
        let object_name = if api_metadata.namespace {
            format!("{}Query", api_metadata.name.to_pascal_case())
        } else {
            String::from("Query")
        };

        insert_field(
            self.query_root_mut().fields_mut().expect("QueryRoot to be an Object"),
            api_metadata.unique_namespace(),
            format!("{object_name}!"),
        );

        insert_empty_object(&mut self.types, object_name)
    }