code: def _realValue_to_float(value_str):
      
      if REAL_VALUE.match(value_str):
          value = float(value_str)
      else:
          value = None
      return value
docs: 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`.