class_docstr: Test StringConverter
class_docstr_tok: ["Test","StringConverter"]
docstr: Tests the use of missing values.
docstr_tok: ["Tests","the","use","of","missing","values","."]
code: def test_missing(self):
      "Tests the use of missing values."
      converter = StringConverter(missing_values=("missing", "missed"))
      converter.upgrade("0")
      assert_equal(converter("0"), 0)
      assert_equal(converter(""), converter.default)
      assert_equal(converter("missing"), converter.default)
      assert_equal(converter("missed"), converter.default)
      try:
          converter("miss")
      except ValueError:
          pass
  
imports: import time
  from datetime import date
  import numpy
  from numpy.testing import assert_, assert_equal, assert_allclose, assert_raises
  from numpy.lib._iotools import LineSplitter, NameValidator, StringConverter, has_nested_fields, easy_dtype, flatten_dtype
label_desc: Use image node_id 3 for calling the TestStringConverter obj's underlying member method code with example usage: obj.test_missing() without return types