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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def decode(cls, auth_header: str, encoding: str='latin1') -> 'BasicAuth': """Create a BasicAuth object from an Authorization HTTP header."""

        try:
            auth_type, encoded_credentials = auth_header.split(' ', 1)
        except ValueError:
            raise ValueError('Could not parse authorization header.')

        if auth_type.lower() != 'basic':
            raise ValueError('Unknown authorization method %s' % auth_type)

        try:
            decoded = base64.b64decode(
                encoded_credentials.encode('ascii'), validate=True
            ).decode(encoding)
        except binascii.Error:
            raise ValueError('Invalid base64 encoding.')

        try:
            # RFC 2617 HTTP Authentication
            # https://www.ietf.org/rfc/rfc2617.txt
            # the colon must be present, but the username and password may be
            # otherwise blank.
            username, password = decoded.split(':', 1)
        except ValueError:
            raise ValueError('Invalid credentials.')

        return cls(username, password, encoding=encoding)