A macro is a form of procedure. implemented by literally substituting the body for each procedure call. Figure 7.52 shows a Pic program and its output. The first two lines define the macros show and small. The bodies of the macros are contained between the two" signs on the lines. Each of the four circles in the figure is drawn using show; the radius of the circle is given by the nonlocal name r. Blocks in Pic are delimited by [ and ]. Each variable assigned to within a block is implicitly declared within the block. From the output. what can you say about the scope of each occurrence of r?
