Why does this game code return IndentationError: expected an indented block

Question

from Bot import *
from random import randint

class Bot2109992(Bot):
    def __init__(self, settings):
        super().__init__(settings)
        self.possibleMoves = [UP, DOWN, RIGHT, LEFT]
        self.setName('Mickey')
    
    def nextMove(self, currentCell, currentEnergy, vision, remainingStainCells):
        #move towards stain cells
        stain_moves = [move for move in self.possibleMoves if currentCell.move(move) in remainingStainCells]
        if stain_moves:
            return stain_moves[0]
        #if currentEnergy < 50:
            #energy_moves = [move for move]
        return self.possibleMoves[randint(0,3)]

I need the robot to clean the cell blocks. I am hoping to ensure it does that in less possible moves and of course save battery