code: def test_proctime(self):
      schema = (
          Schema()
          .field("int_field", DataTypes.INT())
          .field("ptime", DataTypes.BIGINT())
          .proctime()
          .field("string_field", DataTypes.STRING())
      )
  
      properties = schema.to_properties()
      expected = {
          "schema.0.name": "int_field",
          "schema.0.data-type": "INT",
          "schema.1.name": "ptime",
          "schema.1.data-type": "BIGINT",
          "schema.1.proctime": "true",
          "schema.2.name": "string_field",
          "schema.2.data-type": "VARCHAR(2147483647)",
      }
      self.assertEqual(expected, properties)
  
imports: import collections
  import sys
  from pyflink.table.descriptors import Rowtime, Schema
  from pyflink.table.table_schema import TableSchema
  from pyflink.table.types import DataTypes
  from pyflink.testing.test_case_utils import PyFlinkTestCase
label_desc: Use image node_id 5 for calling the SchemaDescriptorTests obj's underlying member method code with example usage: obj.test_proctime() without return types