r"
# Keys are pretty much "any text before the '=' symbol"
(?P<key>[^=]+)
# Match the '=' symbol
=
(?P<value>
# Lazy match
.*?
# Look-ahead (don't move the "regex cursor", just "peek forward")
(?=
# Match a '_' that has no other '_' between it and the '=' character, or...
_[^_=\n]+=
|
# ... or the end of the line
$
)
)
# Actually "consume" the '_' character if it exists (or just match the end-of-line)
(?:_|$)
"
gmx