code: def nullary_func_fixture():
      """
      Register a nullary scalar function.
      """
  
      def nullary_func(context):
          return pa.array(
              [42] * context.batch_length,
              type=pa.int64(),
              memory_pool=context.memory_pool,
          )
  
      func_doc = {
          "summary": "random function",
          "description": "generates a random value",
      }
      func_name = "test_nullary_func"
      pc.register_scalar_function(
          nullary_func, func_name, func_doc, {}, pa.int64()
      )
  
      return nullary_func, func_name
  
imports: import pytest
  import numpy
  import pyarrow
  from pyarrow import compute
label_desc: Use image node_id 9 for calling a global function with example usage: nullary_func_fixture() and returns: nullary_func,  func_name, pa