easiest way to enumerate DEPENDS/RDEPENDS for new python3 recipes?

easiest way to enumerate DEPENDS/RDEPENDS for new python3 recipes?

[Robert P. J. Day]

  apparently, i and a couple other people are responsible for whipping
up a bunch of python3 recipes that currently do not exist; we're going
to standardize on what seems to be the most popular format -- recipes
that inherit both "pypi" and "setuptools3", which make the recipes
pretty straightforward, except for figuring out the proper build and
run-time dependencies in some cases.

  as one example, there is no recipe in the OE layers for
python3-foolscap, but if one pops over to pypi.org, then follows to
the online source:

  https://github.com/warner/foolscap/

the "setup.py" file gives away the RDEPENDS with:

  "install_requires": ["six", "twisted[tls] >= 16.0.0", "pyOpenSSL"],

the other trick i found is to use "pipoe" and see what it comes up
with and, sure enough, for foolscap, pipoe generates a recipe
containing the matching line:

  RDEPENDS_${PN} = "python3-six python3-twisted python3-pyopenssl"

  in other cases, though, it's not at all obvious, for instance with
the existing recipe python3-lxml from meta-python, which spells out
the dependencies:

  DEPENDS += "libxml2 libxslt"
  RDEPENDS_${PN} += "libxml2 libxslt ${PYTHON_PN}-compression"

however, the source for python3-lxml has no informative
"install_requires", whereupon pipoe fails similarly by generating:

  RDEPENDS_${PN} = ""

so, other than trial and error, is there a standard strategy to
determine the dependencies of a new python3 package is the setup.py
file is not forthcoming? (i'm still working my way through learning
python.)

rday