将Python翻译为Lua:替换列表中的字符串字符

def replace_characters(lst, old_char, new_char):
    for i in range(len(lst)):
        lst[i] = lst[i].replace(old_char, new_char)
    return lst

# 测试代码
my_list = ['Hello', 'World', 'Python']
old_char = 'o'
new_char = 'a'
result = replace_characters(my_list, old_char, new_char)
print(result)

function replace_characters(lst, old_char, new_char)
    for i=1, #lst do
        lst[i] = string.gsub(lst[i], old_char, new_char)
    end
    return lst
end

-- 测试代码
my_list = {'Hello', 'World', 'Python'}
old_char = 'o'
new_char = 'a'
result = replace_characters(my_list, old_char, new_char)
for i=1, #result do
    print(result[i])
end