code: def cast_masked_to_masked(context, builder, fromty, toty, val):
      """
      When numba encounters an op that expects a certain type and
      the input to the op is not of the expected type it will try
      to cast the input to the appropriate type. But, in our case
      the input may be a MaskedType, which numba doesn't natively
      know how to cast to a different MaskedType with a different
      `value_type`. This implements and registers that cast.
      """
  
      # We will
      operand = cgutils.create_struct_proxy(fromty)(
          context, builder, value=val
      )
      casted = context.cast(
          builder, operand.value, fromty.value_type, toty.value_type
      )
      ext = cgutils.create_struct_proxy(toty)(context, builder)
      ext.value = casted
      ext.valid = operand.valid
      return ext._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 16 for calling a global function with example usage: cast_masked_to_masked(context, builder, fromty, toty, val) and returns: ext