code: def render(self, r):
      reader = {
          "name": "MatrixRangeReader",
          "nRows": self.n_rows,
          "nCols": self.n_cols,
          "nPartitions": self.n_partitions,
      }
      return escape_str(json.dumps(reader))
  
imports: import abc
  import json
  from .utils import make_filter_and_replace, impute_type_of_partition_interval_array
  from ..expr.types import HailType, tfloat32, tfloat64
  from ..genetics.reference_genome import reference_genome_type
  from ..typecheck import typecheck_method, sequenceof, nullable, enumeration, anytype, oneof, dictof, sized_tupleof
  from ..utils import wrap_to_list
  from ..utils.misc import escape_str
label_desc: Use image node_id 2 for calling the MatrixRangeReader obj's underlying member method code with example usage: obj.render(r) and returns: escape_str