How to use the simpl-schema.prototype function in simpl-schema

* @param {String} fieldName
 */
Mongo.Collection.prototype.removeField = function (fieldName) {

  var collection = this;
  var schema = _.omit(collection.simpleSchema()._schema, fieldName);

  // add field schema to collection schema
  collection.attachSchema(schema, {replace: true});
};

/**
 * @summary Global schemas object. Note: not reactive, won't be updated after initialization
 */

SimpleSchema.prototype.getProfileFields = function () {
  var schema = this._schema;
  var fields = _.filter(_.keys(schema), function (fieldName) {
    var field = schema[fieldName];
    return !!field.profile;
  });
  return fields;
};

/**
 * @summary Get a list of a schema's private fields
 */
Mongo.Collection.prototype.getPrivateFields = function () {
  var schema = this.simpleSchema()._schema;
  var fields = _.filter(_.keys(schema), function (fieldName) {
    var field = schema[fieldName];
    return field.publish !== true;