Convert the string to Value object.

    Args:
        original_string (basestring): Original string
        corenlp_value (basestring): Optional value returned from CoreNLP
    Returns:
        Value

def to_value(original_string, corenlp_value=None):
    """Convert the string to Value object.

    Args:
        original_string (basestring): Original string
        corenlp_value (basestring): Optional value returned from CoreNLP
    Returns:
        Value
    """
    if isinstance(original_string, Value):
        # Already a Value
        return original_string
    if not corenlp_value:
        corenlp_value = original_string
    # Number?
    amount = NumberValue.parse(corenlp_value)
    if amount is not None:
        return NumberValue(amount, original_string)
    # Date?
    ymd = DateValue.parse(corenlp_value)
    if ymd is not None:
        if ymd[1] == ymd[2] == -1:
            return NumberValue(ymd[0], original_string)
        else:
            return DateValue(ymd[0], ymd[1], ymd[2], original_string)
    # String.
    return StringValue(original_string)