def from_json(cls, data):
        """Create a Humidity Condition from a dictionary.

        Args:
            data = {
            "hum_type": string,
            "hum_value": float,
            "barometric_pressure": float,
            "schedule": string,
            "wet_bulb_range": string}
        """
        # Check required and optional keys
        required_keys = ('hum_type', 'hum_value')
        optional_keys = {'barometric_pressure': 101325,
                         'schedule': '', 'wet_bulb_range': ''}
        for key in required_keys:
            assert key in data, 'Required key "{}" is missing!'.format(key)
        for key, val in optional_keys.items():
            if key not in data:
                data[key] = val

        return cls(data['hum_type'], data['hum_value'], data['barometric_pressure'],
                   data['schedule'], data['wet_bulb_range'])