Get the ledger ID of the object

        Example:
        source_id = 'foobar123'
        name = 'Address Schema'
        version = '1.0'
        attrs = ['address', 'city', 'state']
        payment_handle = 0
        schema1 = await Schema.create(source_id, name, version, attrs, payment_handle)
        id1 = await schema.get_schema_id()
        :return: ID string

async def get_schema_id(self):
        """
        Get the ledger ID of the object

        Example:
        source_id = 'foobar123'
        name = 'Address Schema'
        version = '1.0'
        attrs = ['address', 'city', 'state']
        payment_handle = 0
        schema1 = await Schema.create(source_id, name, version, attrs, payment_handle)
        id1 = await schema.get_schema_id()
        :return: ID string
        """
        cb = create_cb(CFUNCTYPE(None, c_uint32, c_uint32, c_char_p))
        c_handle = c_uint32(self.handle)
        id = await do_call('vcx_schema_get_schema_id', c_handle, cb)
        return id.decode()