import math

class Calculator:
    """
    A simple calculator class that performs basic arithmetic operations and memory manipulation.
    
    Attributes:
    - memory (float): The current value stored in the calculator's memory.
    """
    
    def __init__(self):
        """
        Initialize a new Calculator object with memory set to 0.
        """
        self.memory = 0

    def add(self, x):
        """
        Add a value to the calculator's memory.

        Parameters:
        - x (float): The value to add to the calculator's memory.

        Returns:
        - float: The updated value in the calculator's memory.
        """
        self.memory += x
        return self.memory

    def subtract(self, x):
        """
        Subtract a value from the calculator's memory.

        Parameters:
        - x (float): The value to subtract from the calculator's memory.

        Returns:
        - float: The updated value in the calculator's memory.
        """
        self.memory -= x
        return self.memory

    def multiply(self, x):
        """
        Multiply the calculator's memory by a given value.

        Parameters:
        - x (float): The value to multiply the calculator's memory by.

        Returns:
        - float: The updated value in the calculator's memory.
        """
        self.memory *= x
        return self.memory

    def divide(self, x):
        """
        Divide the calculator's memory by a given value.

        Parameters:
        - x (float): The value to divide the calculator's memory by.

        Returns:
        - float: The updated value in the calculator's memory.

        Raises:
        - ValueError: If x is 0 (division by zero is not allowed).
        """
        if x != 0:
            self.memory /= x
            return self.memory
        else:
            raise ValueError("Cannot divide by zero.")

    def root(self, n):
        """
        Take the nth root of the value in the calculator's memory.

        Parameters:
        - n (int): The degree of the root to be taken.

        Returns:
        - float: The updated value in the calculator's memory.

        Raises:
        - ValueError: If trying to take an even root of a negative number.
        """
        if self.memory >= 0 or n % 2 != 0:
            self.memory = math.pow(self.memory, 1/n)
            return self.memory
        else:
            raise ValueError("Cannot take an even root of a negative number.")

    def reset_memory(self):
        """
        Reset the calculator's memory to 0.

        Returns:
        - float: The value 0.
        """
        self.memory = 0
        return self.memory

    def __dir__(self):
        """
        Provide a list of attributes and methods for the Calculator class.

        Returns:
        - list: List of attributes and methods.
        """
        return [
            'memory', 'add', 'subtract', 'multiply', 'divide',
            'root', 'reset_memory', '__init__', '__dir__'
        ]
