class_docstr: Magic allowing easy definition of compositor operations.
  Consult %compositor? for more information.
code: def option_completer(cls, k, v):
      line = v.text_until_cursor
      operation_openers = [
          op.__name__ + "(" for op in Compositor.operations
      ]
  
      modes = ["data", "display"]
      op_declared = any(op in line for op in operation_openers)
      mode_declared = any(mode in line for mode in modes)
      if not mode_declared:
          return modes
      elif not op_declared:
          return operation_openers
      if op_declared and ")" not in line:
          return [")"]
      elif line.split(")")[1].strip() and ("[" not in line):
          return ["["]
      elif "[" in line:
          return ["]"]
  
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 3 for calling the CompositorMagic obj's underlying member method code with example usage: obj.option_completer(cls, k, v) and returns: modes, list, operation_openers, list, list