code: def test_to_csv_escapechar(self):
      df = DataFrame({"col": ['a"a', '"bb"']})
      expected = """\
  "","col"
  "0","a\\"a"
  "1","\\"bb\\""
  """
  
      with tm.ensure_clean("test.csv") as path:  # QUOTE_ALL
          df.to_csv(path, quoting=1, doublequote=False, escapechar="\\")
          with open(path, encoding="utf-8") as f:
              assert f.read() == expected
  
      df = DataFrame({"col": ["a,a", ",bb,"]})
      expected = """\
  ,col
  0,a\\,a
  1,\\,bb\\,
  """
  
      with tm.ensure_clean("test.csv") as path:
          df.to_csv(path, quoting=3, escapechar="\\")  # QUOTE_NONE
          with open(path, encoding="utf-8") as f:
              assert f.read() == expected
  
imports: import io
  import os
  import sys
  from zipfile import ZipFile
  from _csv import Error
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, compat
  import pandas._testing
label_desc: Use image node_id 5 for calling the TestToCSV obj's underlying member method code with example usage: obj.test_to_csv_escapechar() without return types