':return: The input string that should be provided to the
prover9 binary.  This string is formed based on the goal,
assumptions, and timeout value of this object.'

def prover9_input(self, goal, assumptions):

    s = ''
    if assumptions:
        s += 'formulas(assumptions).\n'
        for p9_assumption in convert_to_prover9(assumptions):
            s += ('                %s.\n' % p9_assumption)
        s += 'end_of_list.\n\n'
    if goal:
        s += 'formulas(goals).\n'
        s += ('                %s.\n' % convert_to_prover9(goal))
        s += 'end_of_list.\n\n'
    return s
