def dpll_satisfiable(expr, all_models=False):
    """
    Check satisfiability of a propositional sentence.
    It returns a model rather than True when it succeeds.
    Returns a generator of all models if all_models is True.

    Examples
    ========

    >>> from sympy.abc import A, B
    >>> from sympy.logic.algorithms.dpll2 import dpll_satisfiable
    >>> dpll_satisfiable(A & ~B)
    {A: True, B: False}
    >>> dpll_satisfiable(A & ~A)
    False

    """
    clauses = conjuncts(to_cnf(expr))
    if False in clauses:
        if all_models:
            return (f for f in [False])
        return False
    symbols = sorted(_find_predicates(expr), key=default_sort_key)
    symbols_int_repr = range(1, len(symbols) + 1)
    clauses_int_repr = to_int_repr(clauses, symbols)

    solver = SATSolver(clauses_int_repr, symbols_int_repr, set(), symbols)
    models = solver._find_model()

    if all_models:
        return _all_models(models)

    try:
        return next(models)
    except __HOLE__:
        return False

    # Uncomment to confirm the solution is valid (hitting set for the clauses)
    #else:
        #for cls in clauses_int_repr:
            #assert solver.var_settings.intersection(cls)
dataset/ETHPy150Open sympy/sympy/sympy/logic/algorithms/dpll2.py/dpll_satisfiable