code: def range_matrix_table(
      n_rows, n_cols, n_partitions=None
  ) -> "hail.MatrixTable":
      """Construct a matrix table with row and column indices and no entry fields.
  
      Examples
      --------
  
      >>> range_ds = hl.utils.range_matrix_table(n_rows=100, n_cols=10)
  
      >>> range_ds.count_rows()
      100
  
      >>> range_ds.count_cols()
      10
  
      Notes
      -----
      The resulting matrix table contains the following fields:
  
       - `row_idx` (:py:data:`.tint32`) - Row index (row key).
       - `col_idx` (:py:data:`.tint32`) - Column index (column key).
  
      It contains no entry fields.
  
      This method is meant for testing and learning, and is not optimized for
      production performance.
  
      Parameters
      ----------
      n_rows : :obj:`int`
          Number of rows.
      n_cols : :obj:`int`
          Number of columns.
      n_partitions : int, optional
          Number of partitions (uses Spark default parallelism if None).
  
      Returns
      -------
      :class:`.MatrixTable`
      """
      check_nonnegative_and_in_range(
          "range_matrix_table", "n_rows", n_rows
      )
      check_nonnegative_and_in_range(
          "range_matrix_table", "n_cols", n_cols
      )
      if n_partitions is not None:
          check_positive_and_in_range(
              "range_matrix_table", "n_partitions", n_partitions
          )
      return hail.MatrixTable(
          hail.ir.MatrixRead(
              hail.ir.MatrixRangeReader(n_rows, n_cols, n_partitions),
              _assert_type=hl.tmatrix(
                  hl.tstruct(),
                  hl.tstruct(col_idx=hl.tint32),
                  ["col_idx"],
                  hl.tstruct(row_idx=hl.tint32),
                  ["row_idx"],
                  hl.tstruct(),
              ),
          )
      )
  
imports: import atexit
  import datetime
  import difflib
  import json
  import os
  import re
  import secrets
  import shutil
  import string
  import tempfile
  from collections import defaultdict, Counter
  from contextlib import contextmanager
  from io import StringIO
  from typing import Optional, Literal
  from urllib.parse import urlparse
  import hail
  import hail
  from hail.typecheck import enumeration, typecheck, nullable
  from hail.utils.java import Env, error
label_desc: Use image node_id 1 for calling a global function with example usage: range_matrix_table(n_rows, n_cols, n_partitions) and returns: hail