Example of creating a Gist using Python

init-deep-dive_rust-proc-macro.rs

struct ForIfClause {
    pattern: Pat,
    sequence: Expr,
    conditions: Vec<Condition>,
}

impl Parse for ForIfClause {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        _ = input.parse::<Token![for]>()?;
        let pattern = Pat::parse_single(input)?;
        _ = input.parse::<Token![in]>()?;
        let sequence = input.parse()?;
        let conditions = parse_zero_or_more(input);
        Ok(Self {
            pattern,
            sequence,
            conditions,
        })
    }
}

fn parse_zero_or_more<T: Parse>(input: ParseStream) -> Vec<T> {
    let mut result = Vec::new();
    while let Ok(item) = input.parse() {
        result.push(item);
    }
    result
}