code: def infer_dtype_if_necessary(dtype, values, elements, draw):
      if dtype is None and not values:
          return draw(dtype_for_elements_strategy(elements))
      return dtype
  
imports: from __future__ import absolute_import, division, print_function
  from collections import OrderedDict
  from copy import copy
  import attr
  import numpy
  import pandas
  import hypothesis.extra.numpy
  import hypothesis.internal.conjecture.utils
  import hypothesis.strategies._internal.core
  from hypothesis.control import reject
  from hypothesis.errors import InvalidArgument
  from hypothesis.internal.compat import abc, hrange
  from hypothesis.internal.coverage import check, check_function
  from hypothesis.internal.validation import check_type, check_valid_interval, check_valid_size, try_convert
label_desc: Use image node_id 2 for calling a global function with example usage: infer_dtype_if_necessary(dtype, values, elements, draw) and returns: dtype, draw