def _convert_to_prover9(expression):
    if isinstance(expression, ExistsExpression):
        return 'exists ' + str(expression.variable) + ' ' + _convert_to_prover9(expression.term)
    elif isinstance(expression, AllExpression):
        return 'all ' + str(expression.variable) + ' ' + _convert_to_prover9(expression.term)
    elif isinstance(expression, NegatedExpression):
        return '-(' + _convert_to_prover9(expression.term) + ')'
    elif isinstance(expression, AndExpression):
        return '(' + _convert_to_prover9(expression.first) + ' & ' + \
                     _convert_to_prover9(expression.second) + ')'
    elif isinstance(expression, OrExpression):
        return '(' + _convert_to_prover9(expression.first) + ' | ' + \
                     _convert_to_prover9(expression.second) + ')'
    elif isinstance(expression, ImpExpression):
        return '(' + _convert_to_prover9(expression.first) + ' -> ' + \
                     _convert_to_prover9(expression.second) + ')'
    elif isinstance(expression, IffExpression):
        return '(' + _convert_to_prover9(expression.first) + ' <-> ' + \
                     _convert_to_prover9(expression.second) + ')'
    elif isinstance(expression, EqualityExpression):
        return '(' + _convert_to_prover9(expression.first) + ' = ' + \
                     _convert_to_prover9(expression.second) + ')'
    else:
        return str(expression)
Delete an entire set of data
dataset/ETHPy150Open nltk/nltk/nltk/inference/prover9.py/_convert_to_prover9--crossover with--dataset/ETHPy150Open gmcquillan/firetower/firetower/category.py/Events.delete