import re


def _remove_prefix_username(text: str) -> str:
    """removes twitter style usernames at the start of the tweet"""
    p_text = text
    while re.search(r'^@[a-zA-Z0-9_]{1,15}', p_text):
        p_text = re.sub(r'^@[a-zA-Z0-9_]{1,15}\s*', '', p_text)
    return p_text