def _join_and_preserve_sequential_indent(lines):
    """Joins lines with newlines while preserving indentation of first line"""
    if not lines:
        return ''
    first_line = lines[0]
    leading_spaces = len(first_line) - len(first_line.lstrip(' '))
    return '\n'.join([first_line] + [' ' * leading_spaces + line for line in lines[1:]])