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: overlapping_fields_can_be_merged.rs
    path of file: ./repos/juniper/juniper/src/validation/rules
    
    the code of the file until where you have to start completion: use std::{borrow::Borrow, cell::RefCell, collections::HashMap, fmt::Debug, hash::Hash};

use crate::{
    ast::{Arguments, Definition, Document, Field, Fragment, FragmentSpread, Selection, Type},
    parser::{SourcePosition, Spanning},
    schema::meta::{Field as FieldType, MetaType},
    validation::{ValidatorContext, Visitor},
    value::ScalarValue,
};

#[derive(Debug)]
struct Conflict(ConflictReason, Vec<SourcePosition>, Vec<SourcePosition>);

#[derive(Debug, Clone, PartialEq, Eq, Has
    
    fn different_args_second_adds_an_argument() {
        expect_fails_rule::<_, _, DefaultScalarValue>(
            factory,
            r#"
          fragment conflictingArgs on Dog {
            doesKnowCommand
            doesKnowCommand(dogCommand: HEEL)
          }
        "#,
            &[RuleError::new(
                &error_message(
                    "doesKnowCommand",
                    &Message("they have differing arguments".into()),
                ),
                &[
                    SourcePosition::new(57, 2, 12),
                    SourcePosition::new(85, 3, 12),
                ],
            )],
        );
    }