Function fill 

pub fn fill(
    file: &str,
    text: &str,
    with: &Fill,
    answers: &Answers,
) -> Result<String, ComposeError>

text, the file file, with its placeholders filled: {{name}}, {{crate_name}}, "{{engine.<crate>}}" (with its quotes), {{engine_ref}}, {{engine.docs}} and {{answer.<question>}} (the question’s answers in answers, joined by ,). A GitHub Actions expression, ${{ … }}, passes through as it is. Any other {{ is ComposeError::Placeholder.