for pubmed_id in record['IdList']:

    abstract = Entrez.efetch('pubmed', id=pubmed_id, retmode='text', rettype='abstracts')
    downloaded_abstracts.append(abstract)

    keywords_in_abstract = []
    for ab in downloaded_abstracts:
    keyword_box = []
    words = ab.replace('.','').split(' ')
    for w in words:
            if w.upper() == disease:
                    keyword_box.append(w.upper())
            else:
                    if w in name_kegg:
                            keyword_box.append( name_kegg[w] )

    keywords_in_abstract.append(keyword_box)

이렇게 입력했더니

Traceback (most recent call last):
  File "c:/lecture/python/untitled-11.py", line 55, in <module>
    words = ab.replace('.','').split(' ')

builtins.AttributeError: '_io.TextIOWrapper' object has no attribute 'replace'

이런 오류가 떴습니다.. 이유가 뭘까요? ㅠㅠ