code: def flatten(list_of_2d_array):
      flattened = [array.ravel() for array in list_of_2d_array]
      return flattened
  
file_path: nilearn/examples/02_decoding/plot_miyawaki_reconstruction.py
imports: import sys
  import time
  from nilearn import datasets
  import numpy
  from nilearn.maskers import MultiNiftiMasker
  from sklearn.feature_selection import SelectKBest, f_classif
  from sklearn.linear_model import OrthogonalMatchingPursuit
  from sklearn.pipeline import Pipeline
  from sklearn.preprocessing import StandardScaler
  from sklearn.metrics import accuracy_score, f1_score, precision_score, recall_score
  from matplotlib import pyplot
  from nilearn.plotting import show
label_desc: Use image node_id 1 for calling a global function with example usage: flatten(list_of_2d_array) and returns: flattened