code: def expect_block_mapping(self):
      self.increase_indent(flow=False)
      self.state = self.expect_first_block_mapping_key
  
imports: from .error import YAMLError
  from .events import *
label_desc: Use image node_id 27 for calling the Emitter obj's underlying member method code with example usage: obj.expect_block_mapping() without return types