如何在python中提取两个字符之间的子串？

start_index = string.find(start_char)

end_index = string.find(end_char)

substring = string[start_index + 1:end_index]

def extract_substring(string, start_char, end_char):
    start_index = string.find(start_char)
    end_index = string.find(end_char)
    substring = string[start_index + 1:end_index]
    return substring

string = "Hello, World!"
start_char = "H"
end_char = "o"
substring = extract_substring(string, start_char, end_char)
print(substring)  # 输出为 "ell"