code: def scorer(p, y):
      return np.mean(p - y)
  
file_path: mlens/mlens/parallel/tests/test_b4_layer_push_pop.py
imports: import os
  import numpy
  from mlens.index import INDEXERS
  from mlens.testing.dummy import Data, ECM
  from mlens.utils.dummy import Scale, LogisticRegression
  from mlens.parallel import make_group, Layer, run
  from mlens.externals.sklearn.base import clone
label_desc: Use image node_id 1 for calling a global function with example usage: scorer(p, y) and returns: np