code: def render(self, r):
      reader = {
          "name": "MatrixVCFReader",
          "files": self.path,
          "callFields": self.call_fields,
          "entryFloatTypeName": self.entry_float_type,
          "headerFile": self.header_file,
          "nPartitions": self.n_partitions,
          "blockSizeInMB": self.block_size,
          "minPartitions": self.min_partitions,
          "rg": self.reference_genome.name
          if self.reference_genome
          else None,
          "contigRecoding": self.contig_recoding
          if self.contig_recoding
          else {},
          "arrayElementsRequired": self.array_elements_required,
          "skipInvalidLoci": self.skip_invalid_loci,
          "gzAsBGZ": self.force_bgz,
          "forceGZ": self.force_gz,
          "filterAndReplace": make_filter_and_replace(
              self.filter, self.find_replace
          ),
          "sampleIDs": self._sample_ids,
          "partitionsTypeStr": self._partitions_type._parsable_string()
          if self._partitions_type is not None
          else None,
          "partitionsJSON": self._partitions_json,
      }
      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 MatrixVCFReader obj's underlying member method code with example usage: obj.render(r) and returns: escape_str