That way, separator components are always found at the same relative

indices within the result list.

Emptymatchesfor the pattern split the string only when not adjacent

to a previousempty match.

Adjacent emptymatchesare not possible, but an empty match can occur

immediately after a non-empty match.

..code::pycon

The optional argument *count* is the maximum number of pattern occurrences to be

replaced; *count* must be a non-negative integer. If omitted or zero, all

occurrences will be replaced. Empty matches for the pattern are replaced only

when not adjacent to a previous empty match, so ``sub('x*', '-', 'abxd')`` returns

``'-a-b--d-'``.

occurrences will be replaced.

Adjacent empty matches are not possible, but an empty match can occur

immediately after a non-empty match.

As a result, ``sub('x*', '-', 'abxd')`` returns ``'-a-b--d-'``

instead of ``'-a-b-d-'``.

..index::single: \g; in regular expressions

..versionchanged::3.7

Unknown escapes in *repl* consisting of ``'\'`` and an ASCII letter

now are errors.

Empty matches for the pattern are replaced when adjacent to a previous

non-empty match.

An empty match can occur immediately after a non-empty match.

..versionchanged::3.12

Group *id* can only contain ASCII digits.