def is_instant_time_axis(ctx):
    """
    Deduces from MIP frequency, variable and realm, if the file requires an instantaneous time axis.

    :param dict ctx: The processing context (as a :func:`ProcessingContext` class instance)
    :returns: True if the file requires an instantaneous time axis
    :rtype: *boolean*

    """
    need_instant_time = eval(ctx.cfg.get(ctx.project, 'need_instant_time'))
    if (ctx.attributes['variable'], ctx.attributes['frequency'], ctx.
        attributes['realm']) in need_instant_time:
        return True
    else:
        return False
