code: function swagger20TypeFor(type) {
      if (!type) { return null; }
      if (type === Number) { return 'number'; }
      if (type === Boolean) { return 'boolean'; }
      if (type === String || 
  		type === Date ||
  		type === mongoose.Schema.Types.ObjectId || 
  		type === mongoose.Schema.Types.Oid) { 
  		return 'string'; 
  	}
      if (type === mongoose.Schema.Types.Array || 
  		Array.isArray(type) || 
  		type.name === "Array") { 
  		return 'array'; 
  	}
      if (type === Object  ||
  		type instanceof Object ||
  		type === mongoose.Schema.Types.Mixed ||
  		type === mongoose.Schema.Types.Buffer) { 
  		return null; 
  	}
      throw new Error('Unrecognized type: ' + type);
    }
docs: Convert a Mongoose type into a Swagger type