import re
test_str = ' /product="hypothetical protein"'
match = re.search(r'product="([^"]+)"', test_str)
if match:
print(match.group(1))
--------------------------------------------------------------------------------
product=" 'product="'
--------------------------------------------------------------------------------
( group and capture to \1:
--------------------------------------------------------------------------------
[^"]+ any character except: '"' (1 or more
times (matching the most amount
possible))
--------------------------------------------------------------------------------
) end of \1
--------------------------------------------------------------------------------
" '"'
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