A method has data it receives (i.e. arguments), data it works on and data it sends out (i.e. returns), all these data items more or less equate into variables or data structures like arrays or something.
Remember Aki, you can have a single flowchart for a single method, to document the logic flow in that function. But you might also want to use another diagramming method to document the data flow in that method (i forget what this "diagramming method" is called.)
Then, once you have written enough methods and functions, you will find that in real life, you speak and write using an increasing & unnecessary number of brackets, like i've just done :-)