How does one parse simple inline markup (i.e. *bold*), in Python

*bold*, /italics/, _underline_

Hello, *world*! Let's /go/.

Hello textbf{world}! Let's textit{go}.

>>> import re
>>> str = "Hello, *world*! Let's /go/."
>>> str = re.sub(r"*([^*]*)*", r"textbf{1}", str)
>>> str = re.sub(r"/([^/]*)/",   r"textit{1}", str)
>>> str
"Hello, textbf{world}! Let's textit{go}."