code: def test_simple():
      assert discover(3) == int64
      assert discover(3.0) == float64
      assert discover(3.0 + 1j) == complex128
      assert discover("Hello") == string
      assert discover(True) == bool_
      assert discover(None) == null
  
imports: from collections import OrderedDict
  from itertools import starmap
  from types import MappingProxyType
  from warnings import catch_warnings, simplefilter
  import numpy
  import pytest
  from datashader.datashape.discovery import discover, null, unite_identical, unite_base, unite_merge_dimensions, do_one, lowest_common_dshape
  from datashader.datashape.coretypes import int64, float64, complex128, string, bool_, Tuple, Record, date_, datetime_, time_, timedelta_, int32, var, Option, real, Null, TimeDelta, String, float32, R
  from datashader.datashape.util.testing import assert_dshape_equal
  from datashader.datashape import dshape
  from datetime import date, time, datetime, timedelta
label_desc: Use image node_id 1 for calling a global function with example usage: test_simple() without return types