Evaluate[
expr
] causes expr to be evaluated even if it appears as the argument of a function whose attributes specify that it should be held unevaluated.
Example: Hold[Evaluate[1 + 1]].
You can use Evaluate to override HoldFirst, etc. attributes of built-in functions.
Evaluate only overrides HoldFirst, etc. attributes when it appears directly as the head of the function argument that would otherwise be held.
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