code: def iter_topography(
      info,
      layout=None,
      on_pick=None,
      fig=None,
      fig_facecolor="k",
      axis_facecolor="k",
      axis_spinecolor="k",
      layout_scale=None,
      legend=False,
  ):
      """Create iterator over channel positions.
  
      This function returns a generator that unpacks into
      a series of matplotlib axis objects and data / channel
      indices, both corresponding to the sensor positions
      of the related layout passed or inferred from the channel info.
      Hence, this enables convenient topography plot customization.
  
      Parameters
      ----------
      %(info_not_none)s
      layout : instance of mne.channels.Layout | None
          The layout to use. If None, layout will be guessed.
      on_pick : callable | None
          The callback function to be invoked on clicking one
          of the axes. Is supposed to instantiate the following
          API: ``function(axis, channel_index)``.
      fig : matplotlib.figure.Figure | None
          The figure object to be considered. If None, a new
          figure will be created.
      fig_facecolor : color
          The figure face color. Defaults to black.
      axis_facecolor : color
          The axis face color. Defaults to black.
      axis_spinecolor : color
          The axis spine color. Defaults to black. In other words,
          the color of the axis' edge lines.
      layout_scale : float | None
          Scaling factor for adjusting the relative size of the layout
          on the canvas. If None, nothing will be scaled.
      legend : bool
          If True, an additional axis is created in the bottom right corner
          that can be used to, e.g., construct a legend. The index of this
          axis will be -1.
  
      Returns
      -------
      gen : generator
          A generator that can be unpacked into:
  
          ax : matplotlib.axis.Axis
              The current axis of the topo plot.
          ch_dx : int
              The related channel index.
      """
      return _iter_topography(
          info,
          layout,
          on_pick,
          fig,
          fig_facecolor,
          axis_facecolor,
          axis_spinecolor,
          layout_scale,
          legend=legend,
      )
  
imports: from copy import deepcopy
  from functools import partial
  import numpy
  from scipy import ndimage
  from .._fiff.pick import channel_type, pick_types
  from ..defaults import _handle_default
  from ..utils import Bunch, _check_option, _clean_names, _is_numeric, _to_rgb, fill_doc
  from .utils import DraggableColorbar, _check_cov, _check_delayed_ssp, _draw_proj_checkbox, _plot_masked_image, _setup_ax_spines, _setup_vmin_vmax, add_background_image, plt_show
label_desc: Use image node_id 1 for calling a global function with example usage: iter_topography(info, layout, on_pick, fig, fig_facecolor, axis_facecolor, axis_spinecolor, layout_scale, legend) and returns: _iter_topography