code: def _check_stc_units(
      stc, threshold=1e-7
  ):  # 100 nAm threshold for warning
      max_cur = np.max(np.abs(stc.data))
      if max_cur > threshold:
          warn(
              "The maximum current magnitude is %0.1f nAm, which is very large."
              " Are you trying to apply the forward model to noise-normalized "
              "(dSPM, sLORETA, or eLORETA) values? The result will only be "
              "correct if currents (in units of Am) are used."
              % (1e9 * max_cur)
          )
  
imports: import numbers
  import operator
  import os
  import re
  from builtins import input
  from difflib import get_close_matches
  from importlib import import_module
  from pathlib import Path
  import numpy
  from ..defaults import HEAD_SIZE_DEFAULT, _handle_default
  from ..fixes import _compare_version, _median_complex
  from ._logging import _record_warnings, _verbose_safe_false, logger, verbose, warn
label_desc: Use image node_id 41 for calling a global function with example usage: _check_stc_units(stc, threshold) without return types