\def\dblcolon{\vcentcolon\mathrel{\kern-0.9mu}\vcentcolon} mathrel :: :: mathtools
\def\coloneqq{\vcentcolon\mathrel{\kern-1.2mu}=} mathrel ≔ ≔ mathtools
\def\Coloneqq{\dblcolon\mathrel{\kern-1.2mu}=} mathrel ⩴ ⩴ mathtools
\def\dblcolon{\vcentcolon\mathrel{\kern-0.9mu}\vcentcolon} mathrel :: :: mathtools
\def\coloneqq{\vcentcolon\mathrel{\kern-1.2mu}=} mathrel ≔ ≔ mathtools
\def\Coloneqq{\dblcolon\mathrel{\kern-1.2mu}=} mathrel ⩴ ⩴ mathtools