Get line *line_number* from file named *file_or_script*. Return None if
    there was a problem or it is not found.

    Example:

    lines = pyficache.getline("/tmp/myfile.py")

def getline(file_or_script, line_number, opts=default_opts):
    """Get line *line_number* from file named *file_or_script*. Return None if
    there was a problem or it is not found.

    Example:

    lines = pyficache.getline("/tmp/myfile.py")
    """
    filename = unmap_file(file_or_script)
    filename, line_number = unmap_file_line(filename, line_number)
    lines = getlines(filename, opts)
    if lines and line_number >=1 and line_number <= maxline(filename):
        line = lines[line_number-1]
        if get_option('strip_nl', opts):
            return line.rstrip('\n')
        else:
            return line
        pass
    else:
        return None
    return