code: def print_collection(self, c, h, n):
          
          if c in h:
              return "[]..."
          h.append(c)
          s = []
          for item in c:
              s.append("\n")
              s.append(self.indent(n))
              s.append(self.process(item, h, n - 2))
              s.append(",")
          h.pop()
          return "".join(s)
docs: Print collection using the specified indent (n) and newline (nl).