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: explain.rs
    path of file: ./repos/readyset/nom-sql/src
    
    the code of the file until where you have to start completion: use std::fmt;

use nom::branch::alt;
use nom::bytes::complete::tag_no_case;
use nom::combinator::{opt, value};
use nom::sequence::{terminated, tuple};
use nom_locate::LocatedSpan;
use readyset_util::fmt::fmt_with;
use serde::{Deserialize, Serialize};
use test_strategy::Arbitrary;

use crate::common::{parse_fallible, statement_terminator, until_statement_terminator};
use crate::create::cached_query_inner;
use crate::table::relation;
use crate::whitespace::whitespace1;
use crate::{CacheInner, Dialect, DialectDisplay, NomSqlResult, Relation};

/// EXPLAIN statements
///
/// This is a non-standard ReadySet-specific extension to SQL
#[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize, Arbitrary)]
pub enum ExplainStatement {
    /// Print a graphviz representation of the current query graph to stdout
    Graphviz {
        /// Print a *simplified* graphviz representation, smaller but with less information
        simplified: bool,
        /// Limit the graph to only a single cache
        for_cache: Option<Relation>,
    },
    /// Provides metadata about the last statement that was executed.
    LastStatement,
    /// List domain shard replicas and what worker they're running on
    Domains,
    /// List all CREATE CACHE statements tha
    
    pub fn display(&self, dialect: Dialect) -> impl fmt::Display + Copy + '_ {
        fmt_with(move |f| {
            write!(f, "EXPLAIN ")?;
            match self {
                ExplainStatement::Graphviz {
                    simplified,
                    for_cache,
                } => {
                    if *simplified {
                        write!(f, "SIMPLIFIED ")?;
                    }
                    write!(f, "GRAPHVIZ")?;
                    if let Some(cache) = for_cache {
                        write!(f, " FOR CACHE {}", cache.display(dialect))?;
                    }
                    write!(f, ";")
                }
                ExplainStatement::LastStatement => write!(f, "LAST STATEMENT;"),
                ExplainStatement::Domains => write!(f, "DOMAINS;"),
                ExplainStatement::Caches => write!(f, "CACHES;"),
                ExplainStatement::Materializations => write!(f, "MATERIALIZATIONS;"),
                ExplainStatement::CreateCache { inner, .. } => {
                    write!(f, "EXPLAIN CREATE CACHE FROM ")?;

                    match inner {
                        Ok(inner) => write!(f, "{}", inner.display(dialect)),
                        Err(unparsed) => write!(f, "{unparsed}"),
                    }
                }
            }
        })
    }