from typing import List
import re


def identify_headers(lines: List[str]) -> List[str]:
    """
    Filters a list of lines to the header lines.
    Identifies headers of the 'leading-hashtag' type.
    :param lines: List of header and text lines.
    :returns: List of header lines.
    """

    headers = []
    re_hashtag_headers = r"^#+\ .*$"

    for i, line in enumerate(lines): 
        # identify headers by leading hashtags
        if re.search(re_hashtag_headers, line): 
            headers.append(line)
            
    return headers