code: def test_all_existings_filled_in_server_default(self, pk):
      m1 = MetaData()
      m2 = MetaData()
  
      Table(
          "a",
          m1,
          Column("x", Integer, server_default="5", primary_key=pk),
      )
      Table(
          "a",
          m2,
          Column(
              "x",
              Integer,
              server_default="5",
              comment="new",
              primary_key=pk,
          ),
      )
  
      alter_col = self._assert_alter_col(m1, m2, pk)
      in_("5", alter_col.existing_server_default.arg.text)
  
imports: from sqlalchemy import BigInteger
  from sqlalchemy import Column
  from sqlalchemy import Integer
  from sqlalchemy import MetaData
  from sqlalchemy import Table
  from sqlalchemy.testing import in_
  from ._autogen_fixtures import AutogenFixtureTest
  from ...None import testing
  from ...testing import config
  from ...testing import eq_
  from ...testing import is_
  from ...testing import TestBase
label_desc: Use image node_id 4 for calling the AlterColumnTest obj's underlying member method code with example usage: obj.test_all_existings_filled_in_server_default(pk) without return types