Args:
            provider (ConfigProvider): Provider to add
            front (bool): If True, add provider to front of list

def add(self, provider, front=False):
        """
        Args:
            provider (ConfigProvider): Provider to add
            front (bool): If True, add provider to front of list
        """
        if provider:
            i = self.provider_id_slot(provider)
            if i is not None:
                self.providers[i] = provider

            elif front:
                self.providers.insert(0, provider)

            else:
                self.providers.append(provider)