| 
            plstripa
          ( | id , | 
| pen , | |
| x , | |
| y ); | 
Add a point to a given pen of a given strip chart. There is no need for all pens to have the same number of points or to be equally sampled in the x coordinate. Allocates memory and rescales as necessary.
      Redacted form: plstripa(id, pen, x, y)
    
This function is used in example 17.