import re
from typing import OrderedDict


def extract_email(text):
    """
    Extract email addressed in given text.
    :param text: arbitrary string
    :return: Email addresses in text
    """
    text = re.findall(r"[a-z0-9\.\-+_]+@[a-z0-9\.\-+_]+\.[a-z]+", text)
    return ' '.join(OrderedDict.fromkeys(text))