The present invention relates generally to a stroller for transporting small children and to a wheelchair for transporting physically disabled people and, more particularly, to a package transportation accessory that can be detachably connected to the rear of the stroller or the wheelchair. 
A number of efforts have been made to expand and enhance the function of a stroller used to transport small children.  The conventional stroller is formed with a frame carrying typically four support wheels to provide mobility over the surface of the ground.  Supported on this frame is a seat apparatus of some sort in which the small child is positioned for transport over the ground.  Many different configurations of storage or transportation devices have been devised for attachment to the stroller frame to provide the ability to transport things in addition to the child.  One particular use for such a storage device would be a basket supported beneath and/or behind the child's seat to contain items for transport. 
In some cases, the stroller is configured for conversion between a stroller function and a shopping cart.  U.S. Pat.  No.  6,170,854, granted on Jan. 9, 2001, to Susan H. Maher, et al; and U.S. Pat.  No.  5,544,904, issued on Aug. 13, 1996, to Jay A. Maher, are two examples of strollers that are convertible between the stroller and shopping cart functions.  In the '854 patent, the frame is configured to support a rigid seat device that can be removed to permit fabric and mesh enclosures to be detachably connected to the frame to form a makeshift shopping cart.  Similarly, the '904 patent depicts a stroller structure having a fabric and mesh receptacle that can be stored behind the child's seat in an inoperable position, or deployed over the seat to form a makeshift shopping cart.  In neither of the configurations represented in the '854 or '904 patents can the stroller frame be used simultaneously in both the stroller function, i.e. for the transportation of small children, and the shopping cart function, i.e. to transport a significant number of packages. 
Other devices have been devised to hang from the handle bar or push bar of the stroller apparatus to increase the ability of the stroller to transport items other than the child.  Typically, such devices are small to permit the transport of personal items, such as is taught in U.S. Pat.  No.  4,815,764, issued on Mar. 28, 1989, to Dianne M. Carpenter; U.S. Pat.  No.  4,824,168, issued on Apr. 25, 1989, to Kathyrn J. Makoski; U.S. Pat.  No.  4,830,238, issued on May 16, 1989, to Paul R. Widinski, et al; U.S. Pat.  No.  5,464,183, issued on Nov. 7, 1995, to Thomas E. McConnell, et al; U.S. Pat.  No.  5,702,038, issued on Dec. 30, 1997, to Judith A. Miller, et al; and U.S. Pat.  No.  5,941,437, issued on Aug. 24, 1999, to Kimberly H. Okumura.  While all of these carrying or organizing devices are detachably mounted to the handle apparatus of the stroller, none of these devices are suitable for carrying a significant number of packages, particularly packages of the size typically acquired during shopping. 
Other devices have been created to contain a larger volume of packages or other items besides the child.  Particular reference to such devices can be made to U.S. Pat.  No.  4,346,912, issued on Aug. 31, 1982, to Linda Habib; U.S. Design Pat.  No.  D266,236, granted on Sep. 21, 1982, to Shinroka Nakao, et al; U.S. Pat.  No.  4,953,887, issued on Sep. 4, 1990, to Takehiko Takahashi, et al; and U.S. Pat.  No.  6,155,592, issued on Dec. 5, 2000, to Ben M. Hsia.  In such devices, these basket substitutes are suspended from the frame of the stroller apparatus and are limited in terms of weight and volume due to the limited support received from the stroller frame.  Clearly, these devices are capable of carrying more items that the personal organizers identified above, yet none of these devices are capable of transporting a significant volume of packages. 
One particular need for the expanded or enhanced carrying function of strollers is associated with grocery shopping.  Neither the personal organizers, nor the larger basket substitute, described above, are capable of transporting any significant amount of groceries at the same time as providing a seat for the child.  While grocery shopping presents a good example of a situation where a significant amount of carrying ability is required for items to be transported in addition to the child, other similar situations often arise. 
An accessory that can be detached from the stroller frame should also be capable of storage with the stroller, whether temporarily or on a long term basis.  While the fabric and mesh receptacles of the two Maher patents can be collapsed, the Takahashi and Hsia basket substitutes cannot.  Furthermore, such an accessory needs to be able to accommodate a substantial volume of items without sacrificing the stability of the stroller to which it is mounted.  Limiting either the weight of the volume of the items in the receptacle due to the insubstantial connection between the receptacle and the frame of the stroller, or due to the strength of the stroller frame itself, is a factor that needs to be overcome with respect to providing an accessory for carrying items behind the stroller frame. 
With respect to the need to provide an apparatus to help transport packages or other things, a wheelchair is not unlike a child's stroller.  Both are wheeled carriages having a second person hand grip without adequate capabilities to carry packages and other miscellaneous objects.  Accordingly, the disadvantages of strollers as described above are equally applicable to wheelchairs. 
It would, therefore, be desirable to provide a stroller accessory that will overcome the disadvantages of the prior art to provide an apparatus for transporting a substantial volume of packages or other items at the same time the stroller is being used to transport a child.  It would also be desirable that the stroller accessory be capable of storage on the stroller frame to permit the stroller to be folded in a normal manner for transport in an inoperative position from place to place.