addon/decorators.js
function isStage1ClassDescriptor(possibleDesc) {
  let [target] = possibleDesc;

  return (
    possibleDesc.length === 1 &&
    typeof target === 'function' &&
    'prototype' in target &&
    !target.__isComputedDecorator
  );
}
function isStage1ClassDescriptor(possibleDesc) {
  let [target] = possibleDesc;

  return (
    possibleDesc.length === 1 &&
    typeof target === 'function' &&
    'prototype' in target &&
    !target.__isComputedDecorator
  );
}
function isStage1ClassDescriptor ( possibleDesc ) { let [ target ] = possibleDesc ; return ( possibleDesc . length === 1 && typeof target === 'function' && 'prototype' in target && ! target . __isComputedDecorator ) ; }
These utilities are from @ember-decorators/utils https://github.com/ember-decorators/ember-decorators/blob/f3e3d636a38d99992af326a1012d69bf10a2cb4c/packages/utils/addon/-private/class-field-descriptor.js
These utilities are from