def _realValue_to_float(value_str):
    """
    Convert a value string that conforms to DSP0004 `realValue`, into
    the corresponding float and return it.

    The special values 'INF', '-INF', and 'NAN' are supported.

    Note that the Python `float()` function supports a superset of input
    formats compared to the `realValue` definition in DSP0004. For example,
    "1." is allowed for `float()` but not for `realValue`. In addition, it
    has the same support for Unicode decimal digits as `int()`.
    Therefore, the match patterns explicitly check for US-ASCII digits, and
    the `float()` function should never raise `ValueError`.

    Returns None if the value string does not conform to `realValue`.
    """
    if REAL_VALUE.match(value_str):
        value = float(value_str)
    else:
        value = None
    return value
Convert a value string that conforms to DSP0004 `realValue`, into
    the corresponding float and return it.

    The special values 'INF', '-INF', and 'NAN' are supported.

    Note that the Python `float()` function supports a superset of input
    formats compared to the `realValue` definition in DSP0004. For example,
    "1." is allowed for `float()` but not for `realValue`. In addition, it
    has the same support for Unicode decimal digits as `int()`.
    Therefore, the match patterns explicitly check for US-ASCII digits, and
    the `float()` function should never raise `ValueError`.

    Returns None if the value string does not conform to `realValue`.