def find_start_end(grid):
    """
    Finds the source and destination block indexes from the list.

    Args
        grid:   <list>  the world grid blocks represented as a list of blocks (see Tutorial.pdf)

    Returns
        start: <int>   source block index in the list
        end:   <int>   destination block index in the list
    """
    #------------------------------------
    #
    #   Fill and submit this code
    #
#     return (None, None)
    #-------------------------------------
    counter = 0
    eb_index = None
    rb_index = None
    air_block=[]
    diamond_block=[]
    state=[]
    for i in grid:
        if i =='diamond_block':
            diamond_block.append(counter)
        
        if i =='air':
            air_block.append(counter)

        if i == 'emerald_block':
            eb_index = counter
           
        if i == 'redstone_block':
            rb_index = counter

        state.append(counter)    
        counter+=1
    
    return (eb_index, rb_index,air_block,diamond_block)