<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_default_initial_conditions(self, value=None):
 """Set default initial conditions in the PySB model. Parameters value : Optional[float] Optionally a value can be supplied which will be the initial amount applied. Otherwise a built-in default is used. """

        if value is not None:
            try:
                value_num = float(value)
            except ValueError:
                logger.error('Invalid initial condition value.')
                return
        else:
            value_num = self.default_initial_amount
        if self.model is None:
            return
        for m in self.model.monomers:
            set_base_initial_condition(self.model, m, value_num)