def from_string(cls, address, case_sensitive=False):
        """Alternate constructor for building from a string.

        :param str address: An email address in <user>@<domain> form
        :param bool case_sensitive: passed directly to the constructor argument
            of the same name.
        :returns: An account from the given arguments
        :rtype: :class:`Account`
        """
        assert isinstance(address, str), 'address must be str'
        username, domainname = address.split('@')
        return cls(username, domainname, case_sensitive=case_sensitive)