main.py
def _process(s):
    """
    Remove all characters but letters and numbers, strip whitespace,
    and force everything to lower-case.
    """
    if not s:
        return ''
    return NONWORDCHARS_REGEX.sub(' ', s).lower().strip()

    Remove all characters but letters and numbers, strip whitespace,
    and force everything to lower-case.
    
Remove all characters but letters and numbers, strip whitespace,
and force everything to lower-case.
Remove all characters but letters and numbers strip whitespace and force everything to lower - case .
def _process(s):
    if not s:
        return ''
    return NONWORDCHARS_REGEX.sub(' ', s).lower().strip()
def _process ( s ) : if not s : return '' return NONWORDCHARS_REGEX . sub ( ' ' , s ) . lower ( ) . strip ( )
Remove all characters but letters and numbers, strip whitespace,
and force everything to lower-case.
Remove all characters but letters and numbers strip whitespace and force everything to lower - case .
"""
    Remove all characters but letters and numbers, strip whitespace,
    and force everything to lower-case.
    """
s