code: def ternary_func_fixture():
      """
      Register a ternary scalar function.
      """
  
      def ternary_function(ctx, m, x, c):
          mx = pc.call_function(
              "multiply", [m, x], memory_pool=ctx.memory_pool
          )
          return pc.call_function(
              "add", [mx, c], memory_pool=ctx.memory_pool
          )
  
      ternary_doc = {
          "summary": "y=mx+c",
          "description": "find y from y = mx + c",
      }
      func_name = "y=mx+c"
      pc.register_scalar_function(
          ternary_function,
          func_name,
          ternary_doc,
          {
              "array1": pa.int64(),
              "array2": pa.int64(),
              "array3": pa.int64(),
          },
          pa.int64(),
      )
      return ternary_function, func_name
  
imports: import pytest
  import numpy
  import pyarrow
  from pyarrow import compute
label_desc: Use image node_id 7 for calling a global function with example usage: ternary_func_fixture() and returns: ternary_function,  func_name, pc