code: def test_calc_begin_idx():
      step_size = 1
      idx_diff = 2
  
      idx = 0
      val = scrimp.calc_begin_idx(idx, step_size, idx_diff)
      assert val == 0
  
      idx = 1
      val = scrimp.calc_begin_idx(idx, step_size, idx_diff)
      assert val == 1
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import os
  import pytest
  import numpy
  import matrixprofile
  from matrixprofile import scrimp
label_desc: Use image node_id 25 for calling a global function with example usage: test_calc_begin_idx() without return types