code: def test_na_at_i_start(test_data):
      data = test_data(SHAPE)
      actual = impy.locf(data, axis=1)
      data[0, 0] = data[1, 0]
      assert np.array_equal(actual, data)
  
file_path: impyute/test/imputation/ts/test_locf.py
imports: import numpy
  import impyute
  from impyute.ops.testing import return_na_check
  from impyute.ops import error
label_desc: Use image node_id 2 for calling a global function with example usage: test_na_at_i_start(test_data) without return types