code: def b1_b2_arrs():
      b1 = np.array([[6, 7, 8, 9, 10], [16, 17, 18, 19, 20]])
      b2 = np.array([[1, 2, 3, 4, 5], [14, 12, 13, 14, 17]])
      return b1, b2
  
file_path: earthpy/earthpy/tests/test_norm_diff.py
imports: import numpy
  import numpy.ma
  import pytest
  import earthpy.spatial
label_desc: Use image node_id 1 for calling a global function with example usage: b1_b2_arrs() and returns: b1,  b2