In Vim, how do I match on "=" but not on "=="?

I've tried a number of different search patter开发者_如何学Pythonns:

• [^=]=[^=] works but only if = is not at the beginning/end and it also matches the sandwiching characters
• =\@!==\@! seems like it should work because \@! matches nothing but requires a match, but it doesn't (see :help pattern-overview)
• [^=]\@==[^=]\@= also doesn't but seems like it should

Suggestions?

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Ah hah: =\@<!==\@!

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How about

[^=]\?\zs=\ze[^=]\?

\zs starts the match \ze ends the match