print a single configuration value, based on a prefix and separator

           Parameters
           ==========
           name: the key of the config valur in self.config_values to print
           prefix: the prefix to print
           separator: the separator to use (default is : )

def print_config_value(self, name, prefix='- ', separator=': '):
        """print a single configuration value, based on a prefix and separator

           Parameters
           ==========
           name: the key of the config valur in self.config_values to print
           prefix: the prefix to print
           separator: the separator to use (default is : )
        """

        value_out = 'None'
        if name in self.config_values and self.config_values[name] is not None:
            value_out = self.config_values[name]
        print(prefix + name + separator + value_out)