def find_between(s, first, last):
    """
    Find sting between two sub-strings
    Args:
        s: Main string
        first: first sub-string
        last: second sub-string
    Example find_between('[Hello]', '[', ']')  -> returns 'Hello'
    Returns:
        String between the first and second sub-strings, if any was found otherwise returns an empty string
    """
    try:
        start = s.index(first) + len(first)
        end = s.index(last, start)
        return s[start:end]
    except ValueError:
        return ""