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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add(self, stuff, sloppy=False):
 """Add variables and constraints. Parameters stuff : iterable, Variable, Constraint Either an iterable containing variables and constraints or a single variable or constraint. sloppy : bool Check constraints for variables that are not part of the model yet. Returns ------- None """

        if self._pending_modifications.toggle == 'remove':
            self.update()
            self._pending_modifications.toggle = 'add'
        if isinstance(stuff, collections.Iterable):
            for elem in stuff:
                self.add(elem, sloppy=sloppy)
        elif isinstance(stuff, Variable):
            if stuff.__module__ != self.__module__:
                raise TypeError("Cannot add Variable %s of interface type %s to model of type %s." % (
                    stuff, stuff.__module__, self.__module__))
            self._pending_modifications.add_var.append(stuff)
        elif isinstance(stuff, Constraint):
            if stuff.__module__ != self.__module__:
                raise TypeError("Cannot add Constraint %s of interface type %s to model of type %s." % (
                    stuff, stuff.__module__, self.__module__))
            if sloppy is True:
                self._pending_modifications.add_constr_sloppy.append(stuff)
            else:
                self._pending_modifications.add_constr.append(stuff)
        else:
            raise TypeError("Cannot add %s. It is neither a Variable, or Constraint." % stuff)