code: def is_skew_sym(X):
      """Check if all matrices are skew-symmetric.
  
      Parameters
      ----------
      X : ndarray, shape (..., n, n)
          The set of square matrices, at least 2D ndarray.
  
      Returns
      -------
      ret : boolean
          True if all matrices are skew-symmetric.
      """
      return is_square(X) and np.allclose(X, -np.swapaxes(X, -2, -1))
  
file_path: pyRiemann/pyriemann/utils/test.py
imports: import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: is_skew_sym(X) and returns: unknown