def retrieve_fax(self, fax_filename, folder, fax_id):
    'Retrieve fax content in Base64 format'
    assert (folder in ['IN', 'OUT'])
    params = {'access_id': self.access_id, 'access_pwd': self.access_pwd, 'sFaxFileName': fax_filename, 'sDirection': folder, 'sFaxDetailsID': fax_id}
    SRFax.verify_parameters(params)
    response = self.process_request('Retrieve_Fax', params)
    if (len(response) == 1):
        response = response[0]
    return response
Retrieve fax content in Base64 format
def retrieve_fax(self, fax_filename, folder, fax_id):
    
    assert (folder in ['IN', 'OUT'])
    params = {'access_id': self.access_id, 'access_pwd': self.access_pwd, 'sFaxFileName': fax_filename, 'sDirection': folder, 'sFaxDetailsID': fax_id}
    SRFax.verify_parameters(params)
    response = self.process_request('Retrieve_Fax', params)
    if (len(response) == 1):
        response = response[0]
    return response