code: def expect_first_flow_mapping_key(self):
      if isinstance(self.event, MappingEndEvent):
          self.indent = self.indents.pop()
          self.flow_level -= 1
          self.write_indicator("}", False)
          self.state = self.states.pop()
      else:
          if self.canonical or self.column > self.best_width:
              self.write_indent()
          if not self.canonical and self.check_simple_key():
              self.states.append(self.expect_flow_mapping_simple_value)
              self.expect_node(mapping=True, simple_key=True)
          else:
              self.write_indicator("?", True)
              self.states.append(self.expect_flow_mapping_value)
              self.expect_node(mapping=True)
  
imports: from .error import YAMLError
  from .events import *
label_desc: Use image node_id 20 for calling the Emitter obj's underlying member method code with example usage: obj.expect_first_flow_mapping_key() without return types