code: def expect_block_sequence(self):
      indentless = self.mapping_context and not self.indention
      self.increase_indent(flow=False, indentless=indentless)
      self.state = self.expect_first_block_sequence_item
  
imports: from .error import YAMLError
  from .events import *
label_desc: Use image node_id 24 for calling the Emitter obj's underlying member method code with example usage: obj.expect_block_sequence() without return types