code: def init_mask(s_contrib, value=True):
      """
      Compute True mask of dimensions corresponding to contributions matrix ones.
  
      Parameters
      ----------
      s_contrib: pd.DataFrame
          Matrix with both positive and negative values
      value: bool
          Value used for initialize the mask
  
      Returns
      -------
      pd.DataFrame
          mask of True values.
      """
      if value:
          mask = np.ones(s_contrib.shape, dtype=bool)
      else:
          mask = np.zeros(s_contrib.shape, dtype=bool)
  
      return pd.DataFrame(
          mask, columns=s_contrib.columns, index=s_contrib.index
      )
  
imports: import numpy
  import numpy.ma
  import pandas
label_desc: Use image node_id 2 for calling a global function with example usage: init_mask(s_contrib, value) and returns: pd