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: row.rs
    path of file: ./repos/nushell/crates/nu-command/src/strings/split
    
    the code of the file until where you have to start completion: use nu_engine::CallExt;
use nu_protocol::{
    ast::Call,
    engine::{Command, EngineState, Stack},
    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
    Value,
};
use regex::Regex;
#[derive(Clone)]
pub struct SubCommand;

impl Command for SubCommand {
    fn name(&self) -> &str {
        "split row"
    }

    fn signature(&self) -> Signature {
        Signature::build("split row")
            .input_output_types(vec![
                (Type::String, Type::List(Box::new(Type::String))),
                (
                    Ty
    
    fn signature(&self) -> Signature {
        Signature::build("split row")
            .input_output_types(vec![
                (Type::String, Type::List(Box::new(Type::String))),
                (
                    Type::List(Box::new(Type::String)),
                    (Type::List(Box::new(Type::String))),
                ),
            ])
            .allow_variants_without_examples(true)
            .required(
                "separator",
                SyntaxShape::String,
                "A character or regex that denotes what separates rows.",
            )
            .named(
                "number",
                SyntaxShape::Int,
                "Split into maximum number of items",
                Some('n'),
            )
            .switch("regex", "use regex syntax for separator", Some('r'))
            .category(Category::Strings)
    }