我得到了一個變量賦值錯誤，顯然沒有理解一些東西，但從我的代碼中，我不明白為什么會發生這種情況。代碼：   def something(filename):    with open("tmp/"+filename.stem+".txt", "r") as infile: # opening the tmp file for scraping the data        readfile = infile.readlines() #reads the infile lne by line and returns a list containing the lines        for i, line in enumerate(readfile[1:], 1): # looping over all the lines in the file from position 1 (so skipping 0) to avoid circular feedback            if 'Overview' in line:                start = i                continue                for i, line in enumerate(readfile[1:], 1):                    if 'Identified secondary metabolite regions using strictness' in line:                        end = i                        marker = list(map(lambda s: s.strip('\n'), readfile[start + 1:end])) # stripping the '\n' off every element in the list. map executes a function for each element in a sequence        for i, line in enumerate(readfile[1:], 1): # looping over all the lines in the file from position 1 (so skipping 0) to avoid circular feedback            for location in marker:錯誤：UnboundLocalError: local variable 'marker' referenced before assignment由于第一個 forloop 在第二個 forloop 之前執行導致被設置，因此不應始終在函數范圍內進行賦值？markermarker其次，使用兩個for循環似乎很混亂，我如何在一個for循環中執行此操作？