code: def binstr(m):
      out = []
      for row in m:
          line = [" "] * len(row)
          for i in np.flatnonzero(row):
              line[i] = "."
          out.append("".join(line))
      return "\n".join(out)
  
imports: import os
  from contextlib import nullcontext
  import warnings
  import glob
  import numpy
  import scipy.io
  import scipy.signal
  from typing import Any, ContextManager
  import pytest
  import librosa
label_desc: Use image node_id 25 for calling a global function with example usage: binstr(m) and returns: str