to test:
```
poetry run cpgfe

joern> importCpg("/path/to/cpggen/contrib/python-cpgfrontend/cpgfrontend/cpg.bin.zip")
joern> cpg.method.l
val res1: List[io.shiftleft.codepropertygraph.generated.nodes.Method] = List(
  Method(
    id = 1L,
    astParentFullName = "<empty>",
    astParentType = "<empty>",
    code = "<empty>",
    columnNumber = None,
    columnNumberEnd = None,
    filename = "<empty>",
    fullName = "main",
    hash = None,
    isExternal = false,
    lineNumber = None,
    lineNumberEnd = None,
    name = "<empty>",
    order = -1,
    signature = ""
  )
)
```