docstr: Emit midpoint ticks.
docstr_tok: ["Emit","midpoint","ticks","."]
code: def midpoints(self) -> "Tickfilter":
      """Emit midpoint ticks."""
      return Midpoints((), self)
  
imports: from dataclasses import dataclass, field
  from datetime import datetime
  from typing import ClassVar, List, Optional, Union
  from eventkit import Event, Op
  from ib_insync.contract import Contract
  from ib_insync.objects import DOMLevel, Dividends, FundamentalRatios, MktDepthData, OptionComputation, TickByTickAllLast, TickByTickBidAsk, TickByTickMidPoint, TickData
  from ib_insync.util import dataclassRepr, isNan
label_desc: Use image node_id 5 for calling the TickerUpdateEvent obj's underlying member method code with example usage: obj.midpoints() and returns: Midpoints