code: def on_char(self, event):
      self.delete_selection()
      c = chr(event.GetUnicodeKey())
      self.__tokens.insert(self.__cursor_pos, c)
      self.move_cursor_pos(self.__cursor_pos + 1)
      self.on_token_change()
  
imports: import wx
  import wx.lib.masked
  from cellprofiler_core.constants.measurement import C_FRAME
  from cellprofiler_core.constants.measurement import C_METADATA
  from cellprofiler_core.constants.measurement import C_SERIES
  from cellprofiler_core.constants.measurement import IMAGE
  from cellprofiler_core.preferences import get_primary_outline_color
label_desc: Use image node_id 10 for calling the MetadataControl obj's underlying member method code with example usage: obj.on_char(event) without return types