def parse_triple_string(s: str, start_char: str='|') ->str:
    """
    >>> parse_triple_string("|abc")
    'abc'
    >>> parse_triple_string("|abc\\n    |bcd\\n|cde\\n")
    'abc\\nbcd\\ncde'
    >>> parse_triple_string("@abc\\n    @bcd\\n@cde\\n", '@')
    'abc\\nbcd\\ncde'
    """
    target_lines = s.split('\n')
    if target_lines[0] == '':
        target_lines = target_lines[1:]
    if target_lines[-1] == '':
        target_lines = target_lines[:-1]
    lines = []
    for line in target_lines:
        lines.append(line[line.index(start_char) + 1:])
    return '\n'.join(lines)
