code: def getlocator(xdates, numticks=5, tz=None):
      span = xdates[-1] - xdates[0]
  
      locator, formatter = mdates.date_ticker_factory(
          span=span, tz=tz, numticks=numticks
      )
  
      patch_locator(locator, xdates)
      patch_formatter(formatter, xdates)
      return locator, formatter
  
file_path: backtrader/backtrader/plot/formatters.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import matplotlib.dates
  import matplotlib.ticker
  from ..utils import num2date
label_desc: Use image node_id 3 for calling a global function with example usage: getlocator(xdates, numticks, tz) and returns: locator,  formatter