code: def test_rectcenter():
      a = pt(0, 0)
      b = pt(1, 1)
      r = rect(a, b)
      center = rectcenter(r)
      assert type(center) is np.ndarray
      assert np.array_equal(center, pt(0.5, 0.5))
  
      a = pt(-3, -1)
      b = pt(2, 5)
      r = rect(a, b)
      assert np.array_equal(rectcenter(r), pt(-0.5, 2))
  
imports: import math
  import pytest
  from hypothesis import given
  import hypothesis.strategies
  import numpy
  from pdftabextract.geom import pt, ptdist, vecangle, vecrotate, overlap, lineintersect, rect, rectcenter, rectarea, rectintersect, normalize_angle, normalize_angle_halfcircle, project_polarcoord_lines
label_desc: Use image node_id 9 for calling a global function with example usage: test_rectcenter() without return types