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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.use syn::{  parse::{Parse, ParseStream},  punctuated::Punctuated,  Error, Ident, Result, Token,};
#[derive(Copy, Clone, Debug, Default)]pub struct Attributes {  pub is_unstable: bool,  pub is_v8: bool,  pub must_be_fast: bool,  pub deferred: bool,}
impl Parse for Attributes {  fn parse(input: ParseStream) -> Result<Self> {    let vars = Punctuated::<Ident, Token![,]>::parse_terminated(input)?;
    let vars: Vec<_> = vars.iter().map(Ident::to_string).collect();    let vars: Vec<_> = vars.iter().map(String::as_str).collect();    for var in vars.iter() {      if !["unstable", "v8", "fast", "deferred"].contains(var) {        return Err(Error::new(          input.span(),          "invalid attribute, expected one of: unstable, v8, fast, deferred",        ));      }    }    Ok(Self {      is_unstable: vars.contains(&"unstable"),      is_v8: vars.contains(&"v8"),      must_be_fast: vars.contains(&"fast"),      deferred: vars.contains(&"deferred"),    })  }}