parameters: (docstring)
return_statement: return re.sub(r"[\r\n\t ]+", " ", docstring).strip()
docstring: Normalizes whitespace in the given string.
  
          >>> normalize_docstring('This     is\ta docstring.')
          'This is a docstring.'
docstring_summary: Normalizes whitespace in the given string.
docstring_tokens: Normalizes whitespace in the given string .
function: def normalize_docstring(docstring):
      """
      Normalizes whitespace in the given string.
  
          >>> normalize_docstring('This     is\ta docstring.')
          'This is a docstring.'
      """
      return re.sub(r"[\r\n\t ]+", " ", docstring).strip()
function_tokens: def normalize_docstring ( docstring ) : return re . sub ( r"[\r\n\t ]+" , " " , docstring ) . strip ( )