Walk the abstract syntax tree to find the data dependencies of a python script

analyzer.py

"""
Given the python code:

out.p = inp.x + inp.y
out.q = inp.y + 1

It finds these dependencies:
inputs are x, y
outputs are p, q
"""

import ast
import json
import sys

class DependencyFinder(ast.NodeVisitor):
    inputs = set()
    outputs = set()

    def visit_Attribute(self, node):
        if type(node.value) is ast.Name:
            if node.value.id == 'inp':
                self.inputs.add(node.attr)
            elif node.value.id == 'out':
                self.outputs.add(node.attr)
        self.generic_visit(node)

if len(sys.argv) > 1:
    finder = DependencyFinder()

    with open(sys.argv[1], 'r', encoding='utf-8') as f:
        code = f.read()
        tree = ast.parse(code)
        finder.visit(tree)

    print("inputs are", ', '.join(sorted(finder.inputs)))
    print("outputs are", ', '.join(sorted(finder.outputs)))
else:
    print(f"usage: {sys.argv[0]} <python-file>")