code: def _check_src_type(filters):
      """Check whether src_type is in filters and set custom warning."""
      if "src_type" not in filters:
          filters["src_type"] = None
      warn_text = (
          "The spatial filter does not contain src_type and a robust "
          "guess of src_type is not possible without src. Consider "
          "recomputing the filter."
      )
      return filters, warn_text
  
imports: from copy import deepcopy
  import numpy
  from .._fiff.proj import Projection, make_projector
  from ..cov import Covariance, make_ad_hoc_cov
  from ..forward.forward import _restrict_forward_to_src_sel, is_fixed_orient
  from ..minimum_norm.inverse import _get_vertno, _prepare_forward
  from ..source_space._source_space import label_src_vertno_sel
  from ..time_frequency.csd import CrossSpectralDensity
  from ..utils import _check_option, _check_src_normal, _import_h5io_funcs, _pl, _reg_pinv, _sym_mat_pow, check_fname, logger, verbose, warn
label_desc: Use image node_id 2 for calling a global function with example usage: _check_src_type(filters) and returns: filters,  warn_text