Describe what you want. Jaunt writes the implementation.

import re

import jaunt

jaunt.magic_module(__name__, prompt="All parsers are RFC 5322 strict.")

ADDR_RE = re.compile(r"[^@\s]+@[^@\s]+")   # handwritten constant


class Email:
    """An email message with from_, to, subject, and body string fields.

    Validate on construction: from_ and to must each look like an address.
    """


def parse_email(raw: str) -> Email:
    """Parse a raw RFC 5322 payload into an Email. Read the From, To, and
    Subject headers and the body after the first blank line. Raise ValueError
    on malformed input."""
    ...


def _render_debug(email: Email) -> str:      # real body → handwritten
    return f"<{email.from_} -> {email.to}>"

def parse_email(raw: str) -> Email:
    raw_text = _require_string("raw", raw)
    header_text, body = _split_headers_body(raw_text)
    headers = _parse_headers(header_text)

    from_ = _required_header(headers, "From", allow_empty=False)
    to = _required_header(headers, "To", allow_empty=False)
    subject = _required_header(headers, "Subject", allow_empty=True)

    try:
        return Email(from_, to, subject, body)
    except ValueError as exc:
        raise ValueError(f"Malformed email: {exc}") from exc