def asFloatOrNone(value):
    """Answers a float if it can be converted. Answer None otherwise.

    >>> asFloatOrNone(123)
    123.0
    >>> asFloatOrNone('123')
    123.0
    >>> asFloatOrNone('123a') is None
    True
    """
    try:
        return float(value)
    except (ValueError, TypeError):
        return None
