Function regex 

pub fn regex(
    path: impl StringOrArray,
    query: impl AsRef<str>,
) -> SearchOperator<Regex>

regex interprets the query field as a regular expression. regex is a term-level operator, meaning that the query field isn’t analyzed.

For more details, see the regex operator reference.

These methods can be chained before into_stage to set options:

• allow_analyzed_field
• score