code: def build_spline(
      self,
      x_series,
      y_series,
      boundary_condition_type,
      d_type,
      expected_left_boundary_derivative,
      expected_right_boundary_derivative,
  ):
      if (
          boundary_condition_type
          == cubic.BoundaryConditionType.FIXED_FIRST_DERIVATIVE
      ):
          return tff.math.interpolation.cubic.build_spline(
              x_series,
              y_series,
              boundary_condition_type,
              expected_left_boundary_derivative,
              expected_right_boundary_derivative,
              dtype=d_type,
          )
      else:
          return tff.math.interpolation.cubic.build_spline(
              x_series, y_series, boundary_condition_type, dtype=d_type
          )
  
imports: from absl.testing import parameterized
  import numpy
  import tensorflow.compat.v2
  import tensorflow_probability
  import tf_quant_finance
  from tensorflow.python.framework import test_util
  from tf_quant_finance.math.interpolation import cubic
label_desc: Use image node_id 1 for calling the CubicInterpolationTest obj's underlying member method code with example usage: obj.build_spline(x_series, y_series, boundary_condition_type, d_type, expected_left_boundary_derivative, expected_right_boundary_derivative) and returns: tff, tff