# a very simple program for 
#opening a picture file and 
#displaying it
#
def pickAndShow():
  f=pickAFile()
#
#after the file is selected, f is a string whose
#value is the complete path name of the file
#
  pic=makePicture(f)
#
#makePicture returns a special kind of data
#object whose type is 'picture'
  show(pic)
#
#We could have written it all as a single command:
#show(makePicture(pickAFile()))