code: def convert(self, template_name, parameter_values):
          
  
          if not self.has(template_name):
              raise TemplateNotFoundException(template_name)
  
          template = self.get(template_name)
          return template.to_statement(parameter_values)
docs: Converts the given template to IAM-ready policy statement by substituting template parameters with the given
          values.
  
          :param template_name: Name of the template
          :param parameter_values: Values for all parameters of the template
          :return dict: Dictionary containing policy statement
          :raises ValueError: If the given inputs don't represent valid template
          :raises InsufficientParameterValues: If the parameter values don't have values for all required parameters