code: def setup(self, num_cols):
      num_rows = self.total_cells // num_cols
      self.table = pa.table(
          {
              "c" + str(i): np.random.randn(num_rows)
              for i in range(num_cols)
          }
      )
  
      out = pa.BufferOutputStream()
      pq.write_table(self.table, out)
      self.buf = out.getvalue()
  
imports: import shutil
  import tempfile
  from pandas.util.testing import rands
  import numpy
  import pandas
  import pyarrow
label_desc: Use image node_id 1 for calling the ParquetManyColumns obj's underlying member method code with example usage: obj.setup(num_cols) without return types