import re


def slugify(input : str) -> str:
    s = input.lower()
    s = re.sub(r'\s+', '_', s)
    s = re.sub(r'[^a-z0-9_]+', '', s)
    s = re.sub(r'_+', '_', s)
    s = s.strip('_')
    if not s:
        s = 'buttonplus'
    while len(s) > 1 and s[0].isdigit():
        s = s[1:]
    return s