docstr: Test a simple use case with easy to verify results at different
  relative heights.
docstr_tok: ["Test","a","simple","use","case","with","easy","to","verify","results","at","different","relative","heights","."]
code: def test_basic(self, rel_height, xp, scp):
      """
      Test a simple use case with easy to verify results at different
      relative heights.
      """
      x = xp.array([1, 0, 1, 2, 1, 0, -1])
      out = scp.signal.peak_widths(x, [3], rel_height)
      return out
  
imports: import pytest
  import cupy
  from cupy.cuda import driver
  from cupy.cuda import runtime
  from cupy import testing
  import cupyx.scipy.signal
  import numpy
label_desc: Use image node_id 2 for calling the TestPeakWidths obj's underlying member method code with example usage: obj.test_basic(rel_height, xp, scp) and returns: out