docstr: Helper function to get marker positions depending on mark type.
code: def _get_markers(marks, order, bins):
      """
      Helper function to get marker positions depending on mark type.
      """
      if callable(marks):
          markers = [x for x in order if marks(x)]
      elif isinstance(marks, list):
          markers = [order[x] for x in marks]
      elif isinstance(marks, tuple):
          markers = marks
      else:
          nth_mark = np.ceil(len(order) / marks).astype(int)
          markers = order[::nth_mark]
  
      return np.array([bins[x][1] for x in markers])
  
imports: import numpy
  import param
  from bokeh.models.glyphs import AnnularWedge
  from ...core.data import GridInterface
  from ...core.spaces import HoloMap
  from ...core.util import dimension_sanitizer, is_nan
  from .element import ColorbarPlot, CompositeElementPlot
  from .selection import BokehOverlaySelectionDisplay
  from .styles import base_properties, fill_properties, line_properties, text_properties
label_desc: Use image node_id 13 for calling the RadialHeatMapPlot obj's underlying member method code with example usage: obj._get_markers(marks, order, bins) and returns: np