Babel: Call A when executing B

[Ken Mankoff <mankoff@gmail.com>]

I'd like to have some language specific code (either a code block in the
Library of Babel, in the current file, embedded in elisp in my startup
file, wherever) run each time I execute any code block. Is there a way
to specify this via header arguments, or :prologue, or anything else of
that type?

Reason: Org python Babel configured to work with IPython works great,
but has some limitations, such as src_python{} calls not working. I
think one way to fix this is to have babel run with python, not IPython,
but then pre-load all the packages that make IPython great.

To be specific, how can I executed "import numpy as np" each time I "C-c
C-c" on a "+#BEGIN_SRC python" code block?

Thanks,

  -k.