<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def from_bytes(value):
 """Converts bytes to a string value, if necessary. Args: value (Union[str, bytes]):
 The value to be converted. Returns: str: The original value converted to unicode (if bytes) or as passed in if it started out as unicode. Raises: ValueError: If the value could not be converted to unicode. """

    result = (value.decode('utf-8')
              if isinstance(value, six.binary_type) else value)
    if isinstance(result, six.text_type):
        return result
    else:
        raise ValueError(
            '{0!r} could not be converted to unicode'.format(value))