code: def random_mask(size, missing_per_column, rg):
      base = np.ones(size[0], dtype=bool)
      base[:missing_per_column] = False
      return np.column_stack(
          [rg.permutation(base) for _ in range(size[1])]
      )
  
imports: from pyspark.sql.types import ArrayType, DoubleType
  import glow.gwas.log_reg
  import glow.gwas.functions
  import statsmodels.api
  import pandas
  import numpy
  import pytest
label_desc: Use image node_id 13 for calling a global function with example usage: random_mask(size, missing_per_column, rg) and returns: np