def read_last(file_name, n_lines=1):
    """
    Reads the last line of a file.

    Parameters
    ----------
    :param file_name: string
        Complete path of the file that you would like read.
    :return last_line: string
        Last line of the input file.
    """
    try:
        with open(file_name, mode='r') as infile:
            lines = infile.readlines()
    except IOError:
        last_lines = 'IOEror in read_last_line: this file does not exist.'
        return last_lines
    try:
        last_lines = lines[-n_lines:]
        last_lines = '\n'.join(last_lines)
    except IndexError:
        last_lines = 'IndexError in read_last_line: no last line appears to exist in this file.'
    return last_lines