difficulty extracting content from a file in a folder

Question

Good afternoon, I am using the textract library to extract contents inside a folder and for that I am using a function that inserts the beginning of the directory('./book') and the extension of the file('.pdf') the problem and that even if the file exists it says it does not find the file, this code is part of a larger project and it was when I added this part that stopped working, I believe it is a problem of strings but I do not know identify the problem

import textract

def imprimir(nome):
        inicio="./livro/"
        fim=".pdf"
        ficheiro = inicio+nome+fim
        conteudo=textract.process(ficheiro)
        print(conteudo.decode('utf-8'))


array=['instrucoes']
imprimir(array[0])