code: def make_labelarray(self, strs):
      return LabelArray(strs, missing_value=None)
  
imports: import numpy
  from zipline.lib.labelarray import LabelArray
  from zipline.pipeline import Classifier, Factor, Filter
  from zipline.testing import parameter_space
  from zipline.utils.numpy_utils import categorical_dtype, datetime64ns_dtype, float64_dtype, int64_dtype, NaTns
  from .base import BaseUSEquityPipelineTestCase
label_desc: Use image node_id 5 for calling the FillNATestCase obj's underlying member method code with example usage: obj.make_labelarray(strs) and returns: LabelArray