human
Complete the below
def kernS(s):

    ''''Use a hack to try keep autosimplification from joining Integer or
    minus sign into an Add of a Mul.
this modification doesn\'t
    prevent the 2-arg Mul from becoming an Add, however.
    Examples
    >>> from sympy.core.sympify import kernS
    >>> from sympy.abc import x, y, z
    The 2-arg Mul allows a leading Integer to be distributed but kernS will
    prevent that:
    >>> 2*(x + y)
    2*x + 2*y
    >>> kernS(\'2*(x + y)\')
    2*(x + y)
    If use of the hack fails, the un-hacked string will be passed to sympify...
    and you get what you get.
    XXX This hack should not be necessary once issue 4596 has been resolved.'
    '''

=====
Here you get?
assistant
#Here you get.
    import re
    from sympy.core.symbol import Symbol
    hit = False
    if ('(' in s):
        if (s.count('(') != s.count(')')):
            raise SympifyError('unmatched    left    parenthesis')
        kern = '_kern'
        while (kern in s):
            kern += '_'
        olds = s
        s = re.sub('(\\d+)(    *\\*    *)\\(', ('\\1*%s\\2(' % kern), s)
        kern2 = (kern + '2')
        while (kern2 in s):
            kern2 += '_'
        target = ('%s-%s*(' % (kern, kern))
        s = re.sub('-    *\\(', target, s)
        i = nest = 0
        while True:
            j = s.find(target, i)
            if (j == (-1)):
                break
            j = s.find('(')
            for j in range(j, len(s)):
                if (s[j] == '('):
                    nest += 1
                elif (s[j] == ')'):
                    nest -= 1
                if (nest == 0):
                    break
            s = ((s[:j] + kern2) + s[j:])
            i = j
        s = s.replace(target, target.replace(kern, '(', 1))
        s = s.replace(kern2, ')')
        hit = (kern in s)
    for i in range(2):
        try:
            expr = sympify(s)
            break
        except:
            if hit:
                s = olds
                hit = False
                continue
            expr = sympify(s)
    if (not hit):
        return expr
    rep = {Symbol(kern): 1}
    def _clear(expr):
        if isinstance(expr, (list, tuple, set)):
            return type(expr)([_clear(e) for e in expr])
        if hasattr(expr, 'subs'):
            return expr.subs(rep, hack2=True)
        return expr
    expr = _clear(expr)
    return expr