You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: fee.go
    path of file: ./repos/cosmos-sdk/x/auth/ante
    
    the code of the file until where you have to start completion: package ante

import (
	"bytes"
	"fmt"

	errorsmod "cosmossdk.io/errors"
	"cosmossdk.io/x/auth/types"

	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
)

// TxFeeChecker check if the provided fee is enough and returns the effective fee and tx priority,
// the effective fee should be deducted later, and the priority should be returned in abci response.
type TxFeeChecker func(ctx s
    
func (dfd DeductFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, _ bool, next sdk.AnteHandler) (sdk.Context, error) {
	feeTx, ok := tx.(sdk.FeeTx)
	if !ok {
		return ctx, errorsmod.Wrap(sdkerrors.ErrTxDecode, "Tx must be a FeeTx")
	}

	if ctx.ExecMode() != sdk.ExecModeSimulate && ctx.BlockHeight() > 0 && feeTx.GetGas() == 0 {
		return ctx, errorsmod.Wrap(sdkerrors.ErrInvalidGasLimit, "must provide positive gas")
	}

	var (
		priority int64
		err      error
	)

	fee := feeTx.GetFee()
	if ctx.ExecMode() != sdk.ExecModeSimulate {
		fee, priority, err = dfd.txFeeChecker(ctx, tx)
		if err != nil {
			return ctx, err
		}
	}
	if err := dfd.checkDeductFee(ctx, tx, fee); err != nil {
		return ctx, err
	}

	newCtx := ctx.WithPriority(priority)

	return next(newCtx, tx, ctx.ExecMode() == sdk.ExecModeSimulate)
}