You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the general art of plumbing, and to the particular field of plumbing drains. 
   2. Discussion of the Related Art 
   All sinks, baths and toilets have some sort of plumbing connection to a drain system. This plumbing system generally includes a trap, which is a U-shaped portion of the fluid conduit connecting the sink, etc., to the drain system. The trap serves several purposes. 
   Blockages often occur in the trap. These blockages must be cleared using a force cup, or a snake, or chemicals. These methods may be time consuming and costly. 
   Therefore, there is a need for a drain element that can be easily cleared of blockages. 
   Some buildings have numerous sinks, baths, and toilets. Therefore, it could be extremely costly and time consuming to change all the drain systems in such buildings. Any savings in cost and/or time in performing a change in a plumbing system would be beneficial, especially if there are numerous sinks, etc., such as might be found in a hotel or the like. 
   Therefore, there is a need for a drain element that is easily installed. 
   Still further, some plumbing systems are different from others, even within the same building. This occurs for sinks versus baths, etc. 
   Therefore, there is a need for a drain element that is easily sized to fit a plumbing installation. 
   PRINCIPAL OBJECTS OF THE INVENTION 
   It is a main object of the present invention to provide a drain element that can be easily cleared of blockages. 
   It is another object of the present invention to provide a drain element that is easily installed. 
   It is another object of the present invention to provide a drain element that is easily sized to fit a plumbing installation. 
   SUMMARY OF THE INVENTION 
   These, and other, objects are achieved by a flexible drain element that has two ends and a flexible section which has a stiffness which is less than the stiffness of the drain element adjacent to either end of the drain element. 
   Using the drain element embodying the present invention will permit a user to easily clear any blockage from the drain and will prevent the blockage from backing up against the clearing effort. A user can slide his or her hand along the drain element in the direction of flow to help move any blockage out of the drain element or to aspirate the drain. However, the drain element of the present invention is still easy to install and will be securely held in place on the fluid conduits of the plumbing system. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       FIG. 1  is a perspective view of a plumbing drain embodying the present invention. 
       FIG. 2  is a sectional view taken along line  2 — 2  of  FIG. 1 . 
       FIG. 3  shows the plumbing drain in place in a sink drain system, according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and the accompanying drawings. 
   Referring to the Figures, it can be understood that the present invention is embodied in a flexible drain element  10 . Drain element  10  can be used in connection with a sink, a bathtub, a toilet, or the like. 
   Element  10  includes a hollow tubular one-piece body  12  which can be formed of rubber or other suitably flexible material that will not be damaged by chemicals commonly used in the plumbing system associated with element  10 . 
   Body  12  of element  10  is hollow and has a central bore  14 , a distal end  16 , a proximal end  18 , and a central axis  20  which extends between the distal end  16  and the proximal end  18 . Body  12  has a first stiffness adjacent to the distal end  16  and a second stiffness adjacent to the proximal end  18 . The stiffness of the body  12  adjacent to either end  16 ,  18  can be the same or different as suitable. 
   One-piece body  12  includes a section  24  which has a first end  26  located near and spaced apart from the distal end  16  and a second end  28  that is located near and spaced apart from the proximal end  18  of the body  12 . Section  24  is formed to be flexible and to have a stiffness that is less than either the stiffness of the body  12  adjacent to distal end  16  or the stiffness of the body  12  adjacent to proximal end  18 . In one form of the element  10 , section  24  is formed to be stiffer adjacent to the distal end  16  than adjacent to the proximal end  18  with the stiffness of section  24  of the one-piece body  12  increasing in a flow direction from the proximal end  18  to the distal end  16  as indicated by arrow  30 . The distal and proximal ends  16 ,  18  of the body  12  are flexible but need not change in stiffness along the central axis  20  of the body  12 , and are flexible enough to tightly fit pipes  32  and  34  of the plumbing system. The varying stiffness of section  24  permits the body  12  to be easily manipulated during installation or removal, but will also permit a blockage to be easily cleared from element  10 . 
   In one form of the invention, the stiffness of body  12  between second end  28  and proximal end  18  is uniform and equal to the stiffness of section  24  at second end  28 , and the stiffness of body  12  between first end  26  and distal end  16  is uniform and equal to the stiffness of section  24  at first end  26 . It is noted that “stiffness” of a tubular body can be measured using techniques known to those skilled in the art and thus will not be discussed. The particular method and scales used to measure stiffness of a tube do not form part of the present invention. 
   A first screw-operated clamp  44  surrounds the body  12  adjacent to the distal end  16  of the body  12  and clamps the body  12  to pipe  32 , while a second screw-operated clamp  46  surrounds the body  12  adjacent to the proximal end  18  of the body  12  to attach the body to pipe  34 . 
   Element  10  is shown in combination with a wall-mounted sink  50  in  FIG. 3 ; however, element  10  can be used in any suitable plumbing system and no limitation to sinks is intended by the disclosure in  FIG. 3 . 
   It is understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangements of parts described and shown.

Summary:
A flexible drain element is used in place of a trap and has a section that is flexible with a stiffness that is selected to make clearing blockages easy and expeditious.