code: def cast_na_to_masked(context, builder, fromty, toty, val):
      result = cgutils.create_struct_proxy(toty)(context, builder)
      result.valid = context.get_constant(types.boolean, 0)
  
      return result._getvalue()
  
imports: import operator
  from llvmlite import ir
  from numba.core import cgutils
  from numba.core.typing import signature
  from numba.cuda.cudaimpl import lower, registry
  from numba.extending import lower_builtin, types
  from cudf.core.udf import api
  from cudf.core.udf._ops import arith_ops, bitwise_ops, comparison_ops, unary_ops
  from cudf.core.udf.masked_typing import MaskedType, NAType, _supported_masked_types
label_desc: Use image node_id 15 for calling a global function with example usage: cast_na_to_masked(context, builder, fromty, toty, val) and returns: result