class Timestamp:

    """

    Class contains information about timestamp in several representation variant:
    - Seconds `to_sec`.
    - Milliseconds `to_m_sec`.
    - Microseconds `to_u_sec`.
    - Nanoseconds `to_n_sec` or `value`.

    """

    def __init__(self, nano_secs: int):
        self.__value = nano_secs

    @property
    def to_sec(self) -> float:
        """
        Returns time in seconds.
        """
        return self.__value / (10 ** 9)

    @property
    def to_m_sec(self) -> float:
        """
        Returns time milliseconds seconds.
        """
        return self.__value / (10 ** 6)

    @property
    def to_u_sec(self) -> float:
        """
        Returns time microseconds seconds.
        """
        return self.__value / (10 ** 3)

    @property
    def to_n_sec(self) -> float:
        """
        Returns time nanoseconds seconds.
        """
        return self.__value

    @property
    def value(self) -> float:
        """
        Returns time nanoseconds seconds.
        """
        return self.__value

    @value.setter
    def value(self, value: int):
        """
        Set time in nanoseconds seconds.
        """
        if value <= 0:
            raise ValueError(f"Value of timestamp cannot be less than 0.")
        self.__value = value

    def __str__(self):
        return f"{self.to_u_sec} milliseconds"

    def __eq__(self, other):
        return self.__value == other.__value