问python django中的名称未定义错误

EN

import csv
import io
import re

from django.http import HttpResponse
from django.shortcuts import render
from django.views import generic

from ...forms import CsvUploadForm

import pandas as pd


class CsvImportView(generic.base.View):
    def getemailcolumn(self, sample):
        for key, val in sample:
           print(key, val)
           if re.match("^.+@([?)[a-zA-Z0-9-.]+.([a-zA-Z]{2,3}|[0-9]{1,3})(]?)$", val[0]) is not None:
              return key
        return None


    def post(self, request):
        form = CsvUploadForm(request.POST, request.FILES)

        if form.is_valid():
           fieldnames = ['first_name', 'email', 'last_name']

           csv = pd.read_csv(request.FILES['csv'])

           sample =csv.head();

           emailColumn = getemailcolumn(sample)

           return HttpResponse(sample)
        else:
          ...
          ...