code: def metric_matrix(base_point):
      param_a = base_point[..., 0]
      param_b = base_point[..., 1]
      vector = gs.stack(
          [
              gs.polygamma(1, param_a)
              - gs.polygamma(1, param_a + param_b),
              -gs.polygamma(1, param_a + param_b),
              gs.polygamma(1, param_b)
              - gs.polygamma(1, param_a + param_b),
          ],
          axis=-1,
      )
      return SymmetricMatrices.matrix_representation(vector)
  
file_path: geomstats/geomstats/test_cases/information_geometry/beta.py
imports: import pytest
  import geomstats.backend
  from geomstats.geometry.symmetric_matrices import SymmetricMatrices
  from geomstats.test_cases.information_geometry.dirichlet import DirichletDistributionsTestCase, DirichletMetricTestCase
label_desc: Use image node_id 2 for calling a global function with example usage: metric_matrix(base_point) and returns: SymmetricMatrices