<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def master_key_from_entropy(passphrase='', strength=128):
 """ Generates a master key from system entropy. Args: strength (int):
 Amount of entropy desired. This should be a multiple of 32 between 128 and 256. passphrase (str):
 An optional passphrase for the generated mnemonic string. Returns: HDPrivateKey, str: a tuple consisting of the master private key and a mnemonic string from which the seed can be recovered. """

        if strength % 32 != 0:
            raise ValueError("strength must be a multiple of 32")
        if strength < 128 or strength > 256:
            raise ValueError("strength should be >= 128 and <= 256")
        entropy = rand_bytes(strength // 8)
        m = Mnemonic(language='english')
        n = m.to_mnemonic(entropy)
        return HDPrivateKey.master_key_from_seed(
            Mnemonic.to_seed(n, passphrase)), n