class_docstr: Test remove digits.
class_docstr_tok: ["Test","remove","digits","."]
code: def test_phrases_symbol(self):
      s = pd.Series(
          [
              ["New", "York", "is", "a", "beautiful", "city"],
              ["Look", ":", "New", "York", "!"],
              ["Very", "beautiful", "city", "New", "York"],
          ]
      )
  
      s_true = pd.Series(
          [
              ["New->York", "is", "a", "beautiful", "city"],
              ["Look", ":", "New->York", "!"],
              ["Very", "beautiful", "city", "New->York"],
          ]
      )
  
      self.assertEqual(
          preprocessing.phrases(
              s, min_count=2, threshold=1, symbol="->"
          ),
          s_true,
      )
  
imports: import string
  import pytest
  import pandas
  import numpy
  import doctest
  from texthero import preprocessing, stopwords
  from .None import PandasTestCase
  import warnings
label_desc: Use image node_id 34 for calling the TestPreprocessing obj's underlying member method code with example usage: obj.test_phrases_symbol() without return types