code: function unthenable(input) {
    var output = Object.assign({}, input)
    delete output.then
    if (input !== undefined)
      output.constructor = input.constructor
  
    if (input && input.then instanceof Function) return disguise(output, input,
      true)
  
    // `input` is not thenable
    return input
  }
docs: Return a copy of the input object without `.then()` and `.catch()`
  
  @param {thenable} input
  
  @return {Object} unthenabled input object