input: from typing import List
  
  
  def generate_sum_function(parameter_names: List[str]) -> str:
      """Generates a Python function that returns the sum of the provided parameters.
      >>> generate_sum_function(['x', 'y'])
      'def add(x, y): \\n    \"\"\"Returns the sum of x and y\"\"\"\\n    return x + y\\n'
      """
      
      function_header = f"def add({', '.join(parameter_names)}):"
      docstring = '    """Returns the sum of ' + ' and '.join(parameter_names) + '"""'
      function_body = f"    return {' + '.join(parameter_names)}"
      return f"{function_header}\n{docstring}\n{function_body}\n"
output:     function_header = f"def add({', '.join(parameter_names)}):"
      docstring = '    """Returns the sum of ' + ' and '.join(parameter_names) + '"""'
      function_body = f"    return {' + '.join(parameter_names)}"
      return f"{function_header}\n{docstring}\n{function_body}\n"