class_docstr: Have phi stft as callable w/o using a lambda that does not pickle.
class_docstr_tok: ["Have","phi","stft","as","callable","w\/o","using","a","lambda","that","does","not","pickle","."]
code: def __call__(self, x):  # noqa: D105
      if self.n_dicts == 1:
          return x @ self.ops[0]
      else:
          return np.hstack([x @ op for op in self.ops]) / np.sqrt(
              self.n_dicts
          )
  
imports: import functools
  from math import sqrt
  import numpy
  from ..time_frequency._stft import istft, stft, stft_norm1, stft_norm2
  from ..utils import _check_option, _get_blas_funcs, _validate_type, logger, sum_squared, verbose, warn
  from .mxne_debiasing import compute_bias
label_desc: Use image node_id 2 for calling the _Phi obj's underlying member method code with example usage: obj.__call__(x) and returns: unknown, unknown