what are the Data Flow Diagrams DFD

+-------------+
input --> | Application | --> output
          +-------------+

You can zoom into the function to show detailed dataflow:

          +-------+      +--------+     +----------+
code  --> | lexer | -->  | parser | --> | treetool | --> grapical representation
          +-------+      +--------+     +----------+
              |              ^                 ^
              |              |                 |
              |              V                 |
              |    ================            |
              +--> | symbol table | -----------+
                   ================