class_docstr: Magic for easy customising of normalization, plot and style options.
  Consult %%opts? for more information.
code: def register_custom_spec(cls, spec):
      spec, _ = StoreOptions.expand_compositor_keys(spec)
      errmsg = StoreOptions.validation_error_message(spec)
      if errmsg:
          cls.error_message = errmsg
      cls.opts_spec = spec
  
imports: import sys
  import time
  from IPython.core.magic import Magics, line_cell_magic, line_magic, magics_class
  from IPython.display import HTML, display
  from ..core.options import Options, Store, StoreOptions, options_policy
  from ..core.pprint import InfoPrinter
  from ..operation import Compositor
  from IPython.core import page
label_desc: Use image node_id 2 for calling the OptsMagic obj's underlying member method code with example usage: obj.register_custom_spec(cls, spec) without return types