function Field$1(params) {
    Operator.call(this, null, update$3, params);
  }
Generates one or more field accessor functions.
If the 'name' parameter is an array, an array of field accessors
will be created and the 'as' parameter will be ignored.
@constructor
@param {object} params - The parameters for this operator.
@param {string} params.name - The field name(s) to access.
@param {string} params.as - The accessor function name.