Changes docstr of one functio to that of another

def apply_docstr(docstr_func):
    """
    Changes docstr of one functio to that of another
    """
    def docstr_applier(func):
        #docstr = meta_util_six.get_funcdoc(docstr_func)
        #meta_util_six.set_funcdoc(func, docstr)
        if isinstance(docstr_func, six.string_types):
            olddoc = meta_util_six.get_funcdoc(func)
            if olddoc is None:
                olddoc = ''
            newdoc = olddoc + docstr_func
            meta_util_six.set_funcdoc(func, newdoc)
            return func
        else:
            preserved_func = preserve_sig(func, docstr_func)
            return preserved_func
    return docstr_applier