/**
   * @constructor
   * Represents a join pattern over observable sequences.
   */
  function Pattern(patterns) {
    this.patterns = patterns;
  }

  /**
   *  Creates a pattern that matches the current plan matches and when the specified observable sequences has an available value.
   *  @param other Observable sequence to match in addition to the current pattern.
   *  @return {Pattern} Pattern object that matches when all observable sequences in the pattern have an available value.
   */
  Pattern.prototype.and = function (other) {
    return new Pattern(this.patterns.concat(other));
  };

  /**
   *  Matches when all observable sequences in the pattern (specified using a chain of and operators) have an available value and projects the values.
   *  @param {Function} selector Selector that will be invoked with available values from the source sequences, in the same order of the sequences in the pattern.
   *  @return {Plan} Plan that produces the projected values, to be fed (with other plans) to the when operator.
   */
  Pattern.prototype.thenDo = function (selector) {
    return new Plan(this, selector);
  };