class_docstr: Base test for this type of operator.
code: def _gen_positive_diag(self, dtype, diag_shape):
      if dtype.is_complex:
          diag = linear_operator_test_util.random_uniform(
              diag_shape, minval=1e-4, maxval=1.0, dtype=dtypes.float32
          )
          return math_ops.cast(diag, dtype=dtype)
  
      return linear_operator_test_util.random_uniform(
          diag_shape, minval=1e-4, maxval=1.0, dtype=dtype
      )
  
imports: import numpy
  from tensorflow.python.framework import config
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import variables
  from tensorflow.python.ops.linalg import linalg
  from tensorflow.python.ops.linalg import linear_operator_test_util
  from tensorflow.python.platform import test
label_desc: Use image node_id 2 for calling the BaseLinearOperatorLowRankUpdatetest obj's underlying member method code with example usage: obj._gen_positive_diag(dtype, diag_shape) and returns: linear_operator_test_util, math_ops