code: def test_ravel(self):
      a = masked_array(
          np.matrix([1, 2, 3, 4, 5]), mask=[[0, 1, 0, 0, 0]]
      )
      aravel = a.ravel()
      assert_equal(aravel.shape, (1, 5))
      assert_equal(aravel._mask.shape, a.shape)
  
imports: import pickle
  import numpy
  from numpy.testing import assert_warns
  from numpy.ma.testutils import assert_, assert_equal, assert_raises, assert_array_equal
  from numpy.ma.core import masked_array, masked_values, masked, allequal, MaskType, getmask, MaskedArray, nomask, log, add, hypot, divide
  from numpy.ma.extras import mr_
label_desc: Use image node_id 7 for calling the TestMaskedMatrix obj's underlying member method code with example usage: obj.test_ravel() without return types